Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at asp.q(SourceFile:131)
	at asp.a(SourceFile:168)
	at bjd.a(SourceFile:111)
	at bfd.a(SourceFile:16)
	at bfr.a(SourceFile:6913)
	at bgw.a(SourceFile:284)
	at bgw.b(SourceFile:333)
	at awy.a(SourceFile:332)
	at awy.a(SourceFile:109)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 9/20/13 3:06 PM
Description: Rendering screen

java.lang.NullPointerException
	at asp.q(SourceFile:131)
	at asp.a(SourceFile:168)
	at bjd.a(SourceFile:111)
	at bfd.a(SourceFile:16)
	at bfr.a(SourceFile:6913)
	at bgw.a(SourceFile:284)
	at bgw.b(SourceFile:333)
	at awy.a(SourceFile:332)
	at awy.a(SourceFile:109)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Head --
Stacktrace:
	at asp.q(SourceFile:131)
	at asp.a(SourceFile:168)
	at bjd.a(SourceFile:111)
	at bfd.a(SourceFile:16)
	at bfr.a(SourceFile:6913)
	at bgw.a(SourceFile:284)
	at bgw.b(SourceFile:333)
	at awy.a(SourceFile:332)
	at awy.a(SourceFile:109)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)

-- Screen render details --
Details:
	Screen name: axm
	Mouse location: Scaled: (252, 152). Absolute: (1010, 444)
	Screen size: Scaled: (480, 264). Absolute: (1920, 1054). Scale factor of 4

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdi['JamesD_Mak'/32370, l='MpServer', x=324.79, y=7.62, z=-74.41]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (317,4,-78), Chunk: (at 13,0,2 in 19,-5; contains blocks 304,0,-80 to 319,255,-65), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
	Level time: 919 game time, 919 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 7 total; [rr['Cow'/41121, l='MpServer', x=343.50, y=6.00, z=-126.78], rr['Cow'/41120, l='MpServer', x=343.50, y=6.00, z=-125.22], rr['Cow'/41123, l='MpServer', x=344.78, y=6.00, z=-128.50], bdi['JamesD_Mak'/32370, l='MpServer', x=324.79, y=7.62, z=-74.41], bdi['JamesD_Mak'/32370, l='MpServer', x=325.50, y=-252.25, z=-74.30], rr['Cow'/41122, l='MpServer', x=341.66, y=6.00, z=-135.75], ts['Slime'/49382, l='MpServer', x=297.25, y=6.00, z=-139.65]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bdd.a(SourceFile:284)
	at atv.b(SourceFile:1761)
	at atv.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows XP (x86) version 5.1
	Java Version: 1.6.0_30, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Sun Microsystems Inc.
	Memory: 2800552 bytes (2 MB) / 518979584 bytes (494 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 11203 (627368 bytes; 0 MB) allocated, 96 (5376 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: GeForce GT 520/PCI/SSE2/3DNOW! GL version 4.1.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 281 (15736 bytes; 0 MB) allocated, 56 (3136 bytes; 0 MB) used