game crashes

Minecraft Crash Report ----
// I let you down. Sorry 😞

Time: 11/11/13 4:00 PM
Description: Ticking screen

java.lang.NullPointerException
at bcw.a(SourceFile:671)
at fh.a(SourceFile:28)
at co.b(SourceFile:354)
at bcw.e(SourceFile:98)
at bcy.c(SourceFile:71)
at atv.k(SourceFile:1173)
at atv.S(SourceFile:663)
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 bcw.a(SourceFile:671)
at fh.a(SourceFile:28)
at co.b(SourceFile:354)
at bcw.e(SourceFile:98)
at bcy.c(SourceFile:71)

– Affected screen –
Details:
Screen name: bcy
Stacktrace:
at atv.k(SourceFile:1173)
at atv.S(SourceFile:663)
at atv.d(SourceFile:619)
at net.minecraft.client.main.Main.main(SourceFile:101)

– System Details –
Details:
Minecraft Version: 1.6.4
Operating System: Windows 8 (x86) version 6.2
Java Version: 1.7.0_45, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 19010768 bytes (18 MB) / 69922816 bytes (66 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.6.4
LWJGL: 2.9.0
OpenGL: GeForce GT 635M/PCIe/SSE2 GL version 4.2.0, 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: ~_ERROR~ NullPointerException: