MINECRAFT FORGE AND OPTIFINE HD U A9 ERROR REPORT

---- Minecraft Crash Report ----
// You're mean.

Time: 1/8/14 9:31 AM
Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
	at net.minecraftforge.common.ForgeChunkManager.saveWorld(ForgeChunkManager.java:835)
	at net.minecraftforge.common.ForgeInternalHandler.onDimensionSave(ForgeInternalHandler.java:72)
	at cpw.mods.fml.common.eventhandler.ASMEventHandler_2_ForgeInternalHandler_onDimensionSave_Save.invoke(.dynamic)
	at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:39)
	at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:108)
	at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:839)
	at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:344)
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:590)
	at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:185)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452)
	at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:705)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 35164552 bytes (33 MB) / 259522560 bytes (247 MB) up to 259522560 bytes (247 MB)
	JVM Flags: 1 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump
	AABB Pool Size: 4318 (241808 bytes; 0 MB) allocated, 4135 (231560 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	FML: MCP v9.01-pre FML v7.2.45.996 Minecraft Forge 10.12.0.996 Optifine OptiFine_1.7.2_HD_U_A9 3 mods loaded, 3 mods active
	mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
	FML{7.2.45.996} [Forge Mod Loader] (forge-1.7.2-10.12.0.996.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
	Forge{10.12.0.996} [Minecraft Forge] (forge-1.7.2-10.12.0.996.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1106 (61936 bytes; 0 MB) allocated, 1090 (61040 bytes; 0 MB) used
	Player Count: 1 / 8; [EntityPlayerMP['WillBoy20101'/293, l='WillBoy's World', x=266.90, y=63.94, z=220.50]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Definitely; Client brand changed to 'fml,forge'