[state ]
type=hitdef
trigger1=animelemtime(11)%2=0
trigger1=animelem=11,>=0&&animelem=66,<0
trigger2=animelem=66
attr=s,ha
hitflag=maf
guardflag=
guard.dist=0
damage=0
getpower=0
givepower=0
animtype=light
ground.type=high
air.type=low
priority=3,hit
pausetime=0,12
ground.hittime=17
guard.hittime=17
air.hittime=1
ground.slidetime=17
ground.velocity=0
air.velocity=0,0
fall=0
numhits=0
yaccel=.6
fall.recovertime=45
ground.cornerpush.veloff=0
kill=0
sparkno=-1
hitsound=-1
guard.sparkno=-1
guardsound=-1 

[state ]
type=assertspecial
trigger1=animelem=67,<0
flag=noko
[state ]
type=targetstate
trigger1=numtarget
trigger1=movehit=1||animelemtime(11)%2=1
trigger1=animelem=11,>=0&&animelem=66,<0
value=3152
[state ]
type=targetstate
trigger1=numtarget
trigger1=animelem=66,>0
trigger1=movehit=1
value=3153
[state ]
type=targetstate
trigger1=numtarget
trigger1=animelem=67
value=3154
[state ]
type=envshake
trigger1=animelemtime(11)%4=0
trigger1=animelem=11,>=0&&animelem=66,<0
time=2
ampl=10
freq=60
phase=90
[state ]
type=envshake
trigger1=animelem=66
time=24
ampl=12
freq=75
phase=90

[statedef 3154]
movetype=h
[state ]
type=changeanim
trigger1=1
value=5030
[state ]
type=nothitby
trigger1=1
value=sac
time=1
[state ]
type=velset
trigger1=time>=15
x=-7
y=-9
[state ]
type=selfstate
trigger1=time>=15
value=5050

Make 2 hitdefs, one that triggers to all characters except "X",  and the other one exclusive when hitting "X" character

The specific hitdef for "X" character will contain the line p2stateno = 2600

[state ]
type=hitdef
trigger1=enemy,name!="x"
bla-bla

[state ]
type=hitdef
trigger1=enemy,name="x"
[....]
p2stateno=2600

[SelectBG Sky]; Sky
type  = anim
actionno = 9958
tile=0.01,0.01
velocity = 0,0.5
layerno = 0
start = -320,-10

A: How much ram do you have
B: have you tweaked mugen.cfg at all?

Mugen will consume a lot of memory, although 1.0 has been optimised more than RC8 it'll still use more than winmugen. If you don't have tons of ram, try reducing the precaching. Loading times will be slightly longer but the issue should vanish.

;-=====================================================-
;       Configuration file for mugen.exe
;-=====================================================-

;-------------------------------------------------------
; Game options configurable in M.U.G.E.N's options screen go here.
; Does not include key config.
[Options]
; Basic options
Difficulty = 8
Life = 100
Time = 77
GameSpeed = 0

; Team-only config
Team.1VS2Life = 150
Team.LoseOnKO = 0

; Set the motif to use.
; Motifs are themes that define the look and feel of MUGEN.
; This is not accessible in options screen.
; Note: If you install a motif that overwrites system files (not recommended)
; you may need to set the motif line to use data/system.def instead.
; motif = data/system.def  ;Use this line if using a motif that overwrites system files.
motif = data/screenpack/system.def

;-------------------------------------------------------
[Rules]
 ;Keep this set at VS. It's the only option supported for now.
GameType = VS

 ;This is the amount of power the attacker gets when an attack successfully
 ;hits the opponent. It's a multiplier of the damage done. For example,
 ;for a value of 3, a hit that does 10 damage will give 30 power.
Default.Attack.LifeToPowerMul = .7

 ;This is like the above, but it's for the person getting hit.
 ;These two multipliers can be overridden in the Hitdef controller in the
 ;CNS by using the "getpower" and "givepower" options.
Default.GetHit.LifeToPowerMul = .6

 ;This controls how much damage a super does when you combo into it.
 ;It's actually a multiplier for the defensive power of the opponent.
 ;A large number means the opponent takes less damage. Leave it at
 ;1 if you want supers to do the normal amount of damage when comboed
 ;into.
 ;Note 1: this increase in defence stays effective until the opponent
 ;        gets up from the ground.
 ;Note 2: the program knows you've done a super when the "superpause"
 ;        controller is executed. That's the instance when this change
 ;        becomes effective.
Super.TargetDefenceMul = 1.5


;-------------------------------------------------------
[Config]
 ;Set the game speed here. The default is 60 frames per second. The
 ;larger the number, the faster it goes. Don't use a value less than 10.
GameSpeed = 60

 ;Game native width and height.
 ;Recommended settings are:
 ;  640x480   Standard definition 4:3
 ; 1280x720   High definition 16:9
 ; 1920x1080  Full HD 16:9
GameWidth = 640
GameHeight = 480

 ;Preferred language (ISO 639-1), e.g. en, es, ja, etc.
 ;See http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
Language = "en"

 ;Set to 1 to draw shadows (default). Set to 0 if you have a slow
 ;machine, and want to improve speed by not drawing shadows.
DrawShadows = 0

 ;Number of simultaneous afterimage effects allowed.
 ;Set to a lower number to save memory (minimum 1).
AfterImageMax = 16

 ;Maximum number of layered sprites that can be drawn.
 ;Set to a lower number to save memory (minimum 32).
LayeredSpriteMax = 256

 ;Size of sprite decompression buffer in KB. Increasing this number may help
 ;if you experience slow performance when there are many sprites and/or large
 ;sprites shown over a short period of time.
 ;Minimum 256 for acceptable performance.
 ;If you set this too large you may also experience performance degredation.
SpriteDecompressionBufferSize = 16384

 ;Maximum number of explods allowed in total. Note that hitsparks
 ;also count as explods.
 ;Set to a lower number to save memory (minimum 8).
ExplodMax = 256

 ;Maximum number of system explods allowed.
 ;Set to a lower number to save memory (minimum 8).
SysExplodMax = 128

 ;Maximum number of helpers allowed in total.
 ;Set to a lower number to save memory (minimum 4, maximum 56).
HelperMax = 56

 ;Maximum number of projectiles allowed per player.
 ;Set to a lower number to save memory (minimum 5).
PlayerProjectileMax = 32

 ;This is 1 the first time you run MUGEN.
FirstRun = 0


;-------------------------------------------------------
[Debug]
 ;Set to 0 to disable starting in debug mode by default.
Debug = 0

 ;Set to 0 to disallow switching to debug mode by pressing Ctrl-D.
 ;If Debug = 1, this will be ignored.
AllowDebugMode = 1

 ;Set to 1 to allow debug keys at all times. Otherwise debug keys
 ;allowed only in debug mode.
AllowDebugKeys = 1

 ;Set to 1 to run at maximum speed by default.
Speedup = 0

 ;Default starting stage for quick versus.
StartStage = stages/Hokuto_mamiya'svillage.def


;-------------------------------------------------------
[Video]
 ;The video resolution defaults to the same as the game resolution.
 ;You can force an alternate resolution by uncommenting the lines
 ;below.
;Width  = 1280
;Height = 720

 ;This is the color depth at which to run MUGEN.
 ;Only 16 is supported at this time.
Depth = 16

 ;Set to 1 to enable vertical retrace synchronization. Do not enable
 ;if BlitMode = PageFlip.
 ;Not supported in 1.0.
VRetrace = 0

 ;Set to 1 to enable fullscreen mode, 0 for windowed.
FullScreen = 1;0

 ;Drawing mode
 ;Choose from Normal (fast) and PageFlip (less image "tearing")
BlitMode = Normal

 ;Screen rendering mode.
 ;System - default SDL rendering mode (e.g. windib in Windows)
 ;DirectX - DirectX 5 renderer
 ;OpenGLScreen - hack that allows window resizing but could be slow
RenderMode = System

;-------------------------------------------------------
; Sound configuration
[Sound]
  ;Set the following to 1 to enable sound effects and music.
  ;Set to 0 to disable.
Sound = 1

  ;Set the sample rate of the game audio. Higher rates produce better
  ;quality but require more system resources. Lower the rate if you
  ;are having problems with sound performance.
  ;Recommended values are 22050, 44100, or 48000.
SampleRate = 48000;44100

  ;Sets the audio buffer size. Larger buffers take less CPU but cause
  ;more latency when playing sounds. Smaller buffers give less latency
  ;but take more CPU. Also, if the buffer size is smaller than your system
  ;can handle, you may experience audio problems.
  ;
  ;The buffer size is set to 2^n samples, where n is the value you specify 
  ;here. Valid values for n are between 8 and 15.
  ;
  ;A good rule of thumb is to pick 10 for 22050 Hz audio, or 11 for 44100 Hz
  ;and 48000 Hz. Slower machines may require a larger buffer size.
BufferSize = 11

  ;Set the following to 1 to enable stereo effects in-game
  ;Set to 0 to disable.
StereoEffects = 0;1

  ;This is the width of the sound panning field. If you
  ;Increase this number, the stereo effects will sound
  ;closer to the middle. Set to a smaller number to get
  ;more stereo separation on sound effects.
  ;Only valid if StereoEffects is set to 1.
PanningWidth = 240

  ;Set the following to 1 to reverse left and right channels
  ;on your sound card.
ReverseStereo = 0

  ;Voice Channels to use. Values are from 1 to 16.
  ;If sound quality is poor, try setting a smaller number, such as 8 or 4.
WavChannels = 16;12

  ;This is the master volume for all sounds, in percent (0-100).
MasterVolume = 100

  ;This is the volume for sound effects and voices, in percent (0-100).
WavVolume = 80

  ;This is the master volume for music, (0-100).
BGMVolume = 75

  ;Method used for rate conversion of sound effects.
  ;Choose from:
  ; *) SDL (no interpolation, low quality, low resource usage) 
  ; *) libresample (bandlimited interpolation, medium/high quality, higher
  ;                 resource usage).
SFXResampleMethod = libresample

  ;Quality parameter for resampling, if libresample is used.
  ;Valid values are 0 (medium quality) or 1 (high quality).
SFXResampleQuality = 0

  ;Quality parameter for BGM resampling, using libresample.
  ;Valid values are 0 (medium quality) or 1 (high quality).
BGMResampleQuality = 0


[Music]
  ;Configure music plugins and any optional parameters here. Format looks
  ;like the following:
  ;  plugin = <pluginname> [, <pluginfile1>]
  ;  <optional_param_1> = <value>
  ;  <optional_param_2> = <value>
  ;  plugin = <pluginname2> [, <pluginfile2>]
  ;  ...
  ;Valid parameters depend on the plugin. Each BGM file will be played
  ;by the uppermost plugin in the list that recognizes that file.
  ;For system plugins, the <pluginfile> argument is unused.

  ;System plugin (built-in): mpg123
  ;Plays MP3 files only. Supports looppoints in terms of samples.
  ;Optional parameters:
  ;  decoder = <decodername>
  ;    Requests use of a particular mpg123 decoding engine (request may not be
  ;    honored, depending on the file). This should be omitted unless you 
  ;    know what you are doing. Valid values are:
  ;      SSE, 3DNowExt, 3DNow, MMX, i586, i586_dither, i386, generic, 
  ;      generic_dither.    
  ;  rva = <mode>
  ;    Specifies ReplayGain volume adjustment. Valid values are:
  ;      off   (default; disables ReplayGain)
  ;      track 
  ;      album
  ;  volume = <vol>
  ;    Overall volume adjustment, in percent. This is a linear scale factor 
  ;    that multiplies the output amplitude. Do not specify a value over 
  ;    100.0 unless you know what you are doing.
  ;  extensions = <extensionlist>
  ;    Specifies file extensions to recognize as MP3. This is a comma-
  ;    separated list with no whitespace. For instance,
  ;      extensions = mp3,mpeg3,mpe
  ;    would register the .mp3, .mpeg3, and .mpe file extensions with this
  ;    plugin. Defaults to "mp3" if omitted.
plugin = mpg123
rva = track
extensions =
volume = 100.0

  ;Plugin (add-on): vorbisplug
  ;Plays Ogg Vorbis files using the libvorbisfile library. Supports loop
  ;  points and ReplayGain volume adjustment. Does not support files with
  ;  more than 2 audio channels.
  ;Optional parameters:
  ;  rva = <mode>
  ;    Specifies ReplayGain volume adjustment. Valid values are:
  ;      off   (default; disables ReplayGain)
  ;      track 
  ;      album
  ;  volume = <vol>
  ;    Overall volume adjustment, in percent. This is a linear scale factor 
  ;    that multiplies the output amplitude. Do not specify a value over 
  ;    100.0 unless you know what you are doing.
  ;  extensions = <extensionlist>
  ;    Specifies file extensions to recognize as MP3. This is a comma-
  ;    separated list with no whitespace. For instance,
  ;      extensions = ogg,vorbis,vorb
  ;    would register the .ogg, .vorbis, and .vorb file extensions with this
  ;    plugin. Defaults to "ogg,vorbis" if omitted.
plugin = vorbisplug, plugins/vorbisplug.dll
rva = track
extensions = 
volume = 100.0

  ;System plugin (built-in): sdlmix
  ;Plays MIDI with native playback; MODs and other tracker files 
  ;  (with MikMod)
  ;
  ;Looppoints are not supported. Performs seamless end-to-beginning loops.
  ;
  ;Optional parameters:
  ;  midivolume = <volume>
  ;    Specifies volume scaling for MIDI in percent. 
  ;    100 means no change (default).
  ;  modvolume = <volume> 
  ;    Same as midivolume, but for MODs and other tracker files.
plugin = sdlmix
midivolume =
modvolume = 

;-------------------------------------------------------
[Misc]
  ;Number of extra players to cache in memory.
  ;Set to a lower number to decrease memory usage, at cost of
  ;more frequent loading.
PlayerCache = 1;4

  ;Set to 1 to allow precaching. Precaching attempts to start loading
  ;player data as early as possible, to reduce apparent loading times
  ;between matches. To get the best performance, set PlayerCache to at
  ;least 1. The optimal number for PlayerCache is 4 when precaching is
  ;enabled. Precaching is not available in DOS.
Precache = 1

  ;Set to 1 to enable large-buffer reads of sprite and sound data.
  ;Set to 0 (off) to decrease memory usage, at cost of slower
  ;loading.
BufferedRead = 0;1

  ;Set to 1 to free system.def data from memory whenever possible.
  ;This decreases memory usage, in exchange for loading time
  ;before system screens.
UnloadSystem = 1;0

  ;Configures the handling of sound effects and voices when the
  ;window is in the background (i.e., defocused).
  ;Set to "Mute" to mute sound effects, or "Play" to let sound effects
  ;play.
SFXBackgroundMode = Play

  ;Configures the handling of BGM when the window is in the background.
  ;Set to "Pause" to pause the music, "Mute" to mute the music but leave
  ;it running at normal speed, or "Play" to continue playing as usual.
  ;If you are running in fullscreen mode, then this setting is always
  ;set to "Pause".
BGMBackgroundMode = Play

;-------------------------------------------------------
[Arcade]
 ;Set to 0 for computer to choose color 1 if possible.
 ;Set to 1 for computer to randomly choose a color.
AI.RandomColor = 0

 ;This option allows the AI to input commands without
 ;having to actually press any keys (in effect, cheating).
 ;Set to 1 to enable, 0 to disable.
AI.Cheat = 1

 ;Arcade Mode AI ramping. For both parameters below, the first number
 ;corresponds to the number of matches won, and the second number to the
 ;AI difficulty offset. The actual difficulty is the sum of the AI
 ;difficulty level (set in the options menu) and the value of the offset
 ;at a particular match.
 ;  AIramp.start = start_match, start_diff
 ;  AIramp.end   = end_match, end_diff
 ;The difficulty offset function is a constant value of start_diff from
 ;the first match until start_match matches have been won. From then the
 ;offset value increases linearly from start_diff to end_diff. After
 ;end_diff matches have been won, the offset value is end_diff.
 ;  e_d            /----------
 ;               /
 ;  s_d _______/
 ;     ^      ^     ^        ^
 ;   1st_m   s_m   e_m     last_m
 ;For example, if you have:
 ;  AIramp.start = 2,0
 ;  AIramp.end   = 4,2
 ;For 6 matches at level 4, the difficulty will be (by match):
 ;  4,4,4,5,6,6
arcade.AIramp.start = 2, 0
arcade.AIramp.end   = 4, 2

 ;Team Mode AI ramping
team.AIramp.start = 1, 0
team.AIramp.end   = 3, 2

 ;Survival Mode AI ramping
survival.AIramp.start = 0, -3
survival.AIramp.end   = 16, 4


;-------------------------------------------------------
[Input]
P1.UseKeyboard = 1
P2.UseKeyboard = 1
;Joystick type:
;0 - Disabled
;1 - Enabled
P1.Joystick.type = 1
P2.Joystick.type = 1

;-------------------------------------------------------
; P1 Key config (configurable from M.U.G.E.N)
[P1 Keys]
Jump   = 103
Crouch = 117
Left   = 121
Right  = 107
A      = 122
B      = 120
C      = 99
X      = 118
Y      = 110
Z      = 109
Start  = 13

; P2 Key config (configurable from M.U.G.E.N)
[P2 Keys]
Jump   = 264
Crouch = 258
Left   = 260
Right  = 262
A      = 111
B      = 112
C      = 91
X      = 108
Y      = 59
Z      = 39
Start  = 271

[P1 Joystick]
Jump   = 1
Crouch = 2
Left   = 3
Right  = 4
A      = 13
B      = 14
C      = 20
X      = 15
Y      = 16
Z      = 18
Start  = 24

[P2 Joystick]
Jump   = 33
Crouch = 34
Left   = 35
Right  = 36
A      = 41
B      = 42
C      = 48
X      = 43
Y      = 44
Z      = 46
Start  = 50