Mon ordi bug sur minecraft

Bonjour,

Malgré le fait que j'ai réinitialiser mon ordinateur minecraft ne marche toujours pas au début (pendant 1 minutes)je bug mais ensuite sa arrete sa affiche le message suivant Minecraft has crashed!
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Minecraft has stopped running because it encountered a problem; Exception in server tick loop
This error has been saved to C:\Users\Numero8\AppData\Roaming\.minecraft\crash-reports\crash-2012-11-01_17.31.37-server.txt for your convenience. Please include a copy of this file if you report this crash to anyone.



--- BEGIN ERROR REPORT b17b0505 --------
Generated 12-11-01 17:31

- Minecraft Version: 1.4.2
- Operating System: Windows 7 (x86) version 6.1
- Java Version: 1.7.0_09, Oracle Corporation
- Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
- Memory: 71480424 bytes (68 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
- JVM Flags: 2 total; -Xms512m -Xmx1024m
- AABB Pool Size: 13845150 (775328400 bytes; 739 MB) allocated, 13845150 (775328400 bytes; 739 MB) used
- Is Modded: Probably not
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 9778 (547568 bytes; 0 MB) allocated, 3418 (191408 bytes; 0 MB) used
- Player Count: 1 / 8; [ih['hotcraft111'/8314, l='world of yt', x=-158,90, y=65,00, z=150,80]]
- World world of yt Entities: 0 total; []
- World world of yt Players: 0 total; []
- World world of yt Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Integrated Server

java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Unknown Source)
at java.util.Arrays.copyOf(Unknown Source)
at java.util.ArrayList.grow(Unknown Source)
at java.util.ArrayList.ensureCapacityInternal(Unknown Source)
at java.util.ArrayList.add(Unknown Source)
at amt.a(SourceFile:24)
at alf.e(SourceFile:546)
at alf.a(SourceFile:541)
at xe.a(SourceFile:854)
at lb.d(SourceFile:524)
at ln.e(SourceFile:938)
at ln.c(SourceFile:1132)
at ps.c(SourceFile:25)
at pw.c(SourceFile:145)
at ln.j_(SourceFile:531)
at ps.j_(SourceFile:30)
at xe.a(SourceFile:1218)
at ie.a(SourceFile:424)
at xe.g(SourceFile:1197)
at xe.h(SourceFile:1122)
at ie.h(SourceFile:352)
at net.minecraft.server.MinecraftServer.r(SourceFile:718)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at bcb.q(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)
--- END ERROR REPORT ba3eca7b ----------

que faire? merci d'avance