Game Crashes

I am trying to play my singleplayer world and all it does is crash. This is what it gives me and I also attached the full crash-report.

--- BEGIN ERROR REPORT d2285ce6 --------
Full report at:
C:\Users\Nate\AppData\Roaming\.minecraft\crash-reports\crash-2012-11-01_16.20.53-client.txt

java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(Unknown Source)
	at java.lang.Integer.parseInt(Unknown Source)
	at java.lang.Integer.parseInt(Unknown Source)
	at bad.b(SourceFile:1475)
	at bad.a(SourceFile:1364)
	at xv.a(SourceFile:809)
	at pi.c(SourceFile:107)
	at mc.j_(SourceFile:524)
	at xv.a(SourceFile:1315)
	at xv.g(SourceFile:1294)
	at xv.h(SourceFile:1194)
	at net.minecraft.client.Minecraft.l(SourceFile:1283)
	at net.minecraft.client.Minecraft.J(SourceFile:582)
	at net.minecraft.client.Minecraft.run(SourceFile:534)
	at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 28781c6a ----------