Hopper: java.lang.RuntimeException: Failed to check session lock, aborting

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-398134/

Crash:

java.lang.RuntimeException: Failed to check session lock, aborting
	at awv.h(SourceFile:48)
	at awv.<init>(SourceFile:34)
	at awr.<init>(SourceFile:16)
	at aws.a(SourceFile:71)
	at ayw.a(SourceFile:1577)
	at bbb.a(SourceFile:202)
	at bbw.a(SourceFile:172)
	at bbb.a(SourceFile:301)
	at bbw.d(SourceFile:236)
	at bbw.k(SourceFile:211)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 18.10.2013 20:02
Description: Updating screen events

java.lang.RuntimeException: Failed to check session lock, aborting
	at awv.h(SourceFile:48)
	at awv.<init>(SourceFile:34)
	at awr.<init>(SourceFile:16)
	at aws.a(SourceFile:71)
	at ayw.a(SourceFile:1577)
	at bbb.a(SourceFile:202)
	at bbw.a(SourceFile:172)
	at bbb.a(SourceFile:301)
	at bbw.d(SourceFile:236)
	at bbw.k(SourceFile:211)
	at ayw.o(SourceFile:1302)
	at ayw.ad(SourceFile:755)
	at ayw.e(SourceFile:706)
	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 awv.h(SourceFile:48)
	at awv.<init>(SourceFile:34)
	at awr.<init>(SourceFile:16)
	at aws.a(SourceFile:71)
	at ayw.a(SourceFile:1577)
	at bbb.a(SourceFile:202)
	at bbw.a(SourceFile:172)
	at bbb.a(SourceFile:301)
	at bbw.d(SourceFile:236)
	at bbw.k(SourceFile:211)

-- Affected screen --
Details:
	Screen name: bta
Stacktrace:
	at ayw.o(SourceFile:1302)
	at ayw.ad(SourceFile:755)
	at ayw.e(SourceFile:706)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 13w42b
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.6.0_31, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 123773616 bytes (118 MB) / 254476288 bytes (242 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 10011 (560616 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 13w42b
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics Family GL version 3.1.0 - Build 8.15.10.2430, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: [Faithful_2.zip]
	Current Language: suomi (FI)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
	Anisotropic Filtering: Off (1)

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-398134/19094174/