My Minecraft keeps crashing?

[]+_+[]isbobIm playing Minecraft and everything stops and it said it crashed?
The Crash Report,
---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 12/19/12 10:36 AM
Description: Ticking memory connection

java.lang.NullPointerException
at iv.a(NetServerHandler.java:586)
at fl.a(SourceFile:58)
at cf.b(MemoryConnection.java:79)
at iv.d(NetServerHandler.java:82)
at iw.b(NetworkListenThread.java:55)
at bdr.b(IntegratedServerListenThread.java:111)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:704)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:600)
at bdo.q(IntegratedServer.java:110)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:499)
at fy.run(SourceFile:856)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
Minecraft Version: 1.4.5
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_05, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 235672560 bytes (224 MB) / 529727488 bytes (505 MB) up to 954466304 bytes (910 MB)
JVM Flags: 2 total; -Xms512m -Xmx1024m
AABB Pool Size: 3779 (211624 bytes; 0 MB) allocated, 3544 (198464 bytes; 0 MB) used
Suspicious classes: FML and Forge are installed
IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
FML: MCP v7.23 FML v4.5.21.486 Minecraft Forge 6.4.1.436 5 mods loaded, 5 mods active
mcp [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
ChristmasCraft [ChristmasCraft] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
MCA [MCA - Minecraft Comes Alive] (mca v3.0.3.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available
Profiler Position: N/A (disabled)
Vec3 Pool Size: 997 (55832 bytes; 0 MB) allocated, 927 (51912 bytes; 0 MB) used
Player Count: 1 / 8; [iq['coolguy1112'/349, l='EARTH', x=-202.88, y=72.00, z=266.73]]
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'forge,fml'