"Minecraft has been crashed" Aidez moi svp

Bonjour, je débute dans Minecraft et je voudrait jouer a une sauvegarde. Il met beaucoup de temps a charger et un message d'erreur s'affiche. Voici le rapport :

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 03/08/12 12:31
Description: Exception in server tick loop

java.lang.OutOfMemoryError: unable to create new native thread
at java.lang.Thread.start0(Native Method)
at java.lang.Thread.start(Unknown Source)
at aes.<init>(SourceFile:17)
at aes.<clinit>(SourceFile:6)
at wx.a(SourceFile:109)
at wx.a(SourceFile:91)
at gp.b(SourceFile:127)
at gp.a(SourceFile:153)
at gq.a(SourceFile:510)
at net.minecraft.server.MinecraftServer.a(SourceFile:242)
at net.minecraft.server.MinecraftServer.p(SourceFile:388)
at axu.p(SourceFile:111)
at net.minecraft.server.MinecraftServer.run(SourceFile:316)
at ep.run(SourceFile:539)

Relevant Details:
- Minecraft Version: 1.3.1
- Operating System: Windows XP (x86) version 5.1
- Java Version: 1.6.0_22, Sun Microsystems Inc.
- Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
- Memory: 364210648 bytes (347 MB) / 519110656 bytes (495 MB) up to 1037959168 bytes (989 MB)
- JVM Flags: 2 total; -Xms512m -Xmx1024m
- Type: Integrated Server
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Player Count: 1 / 8; [gt['Maxi4216'/208, l='Nouveau monde', x=259,96, y=64,00, z=48,88]]
- World Nouveau monde Entities: 0 total; []
- World Nouveau monde Players: 0 total; []
- World Nouveau monde Chunk Stats: ServerChunkCache: 0 Drop: 0