Hopper: java.lang.NullPointerException: Updating screen events

java.lang.NullPointerException: Updating screen events
	at bbj.a(SourceFile:68)
	at bbd.a(SourceFile:42)
	at bcd.a(SourceFile:172)
	at bcd.d(SourceFile:236)
	at bcd.k(SourceFile:211)

---- Minecraft Crash Report ----
// There are four lights!

Time: 10/27/13 11:14 AM
Description: Updating screen events

java.lang.NullPointerException: Updating screen events
	at bbj.a(SourceFile:68)
	at bbd.a(SourceFile:42)
	at bcd.a(SourceFile:172)
	at bcd.d(SourceFile:236)
	at bcd.k(SourceFile:211)
	at azd.o(SourceFile:1303)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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

-- Head --
Stacktrace:
	at bbj.a(SourceFile:68)
	at bbd.a(SourceFile:42)
	at bcd.a(SourceFile:172)
	at bcd.d(SourceFile:236)
	at bcd.k(SourceFile:211)

-- Affected screen --
Details:
	Screen name: btj
Stacktrace:
	at azd.o(SourceFile:1303)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 208327080 bytes (198 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: 678711 (38007816 bytes; 36 MB) allocated, 2 (112 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 1.7.2
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics Family GL version 3.0.0 - Build 8.15.10.2342, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
	Anisotropic Filtering: Off (1)