Crashing Upon Joining

[Asbowl2468]

1. I get this message when trying to join your Survival Servers
2. But it worked 10 minuites ago

Error Message

---- Minecraft Crash Report ----
// My bad.
 
Time: 04/11/12 16:44
Description: Unexpected error
 
java.lang.NullPointerException
    at aww.a(SourceFile:57)
    at ayt.b(SourceFile:755)
    at net.minecraft.client.Minecraft.J(SourceFile:604)
    at net.minecraft.client.Minecraft.run(SourceFile:534)
    at java.lang.Thread.run(Unknown Source)
 
Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Windows 7 (amd64) version 6.1
- Java Version: 1.6.0_30, Sun Microsystems Inc.
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
- Memory: 455803136 bytes (434 MB) / 514523136 bytes (490 MB) up to 954466304 bytes (910 MB)
- JVM Flags: 2 total; -Xms512m -Xmx1024m
- AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
- LWJGL: 2.4.2
- OpenGL: AMD Radeon HD 6570 GL version 4.2.11762 Compatibility Profile Context, ATI Technologies Inc.
- Is Modded: Probably not
- Type: Client
- Texture Pack: Default
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: ~ERROR~ NullPointerException: null