Mincraft keeps on crashing 1.6.1

 ---- Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 7/2/13 5:38 PM
Description: Rendering screen

java.lang.OutOfMemoryError: unable to create new native thread
	at java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(Unknown Source)
	at avf.d(SourceFile:390)
	at avf.a(SourceFile:339)
	at avx.a(SourceFile:274)
	at ave.a(SourceFile:263)
	at bet.b(SourceFile:718)
	at atn.S(SourceFile:685)
	at atn.d(SourceFile:618)
	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 java.lang.Thread.start0(Native Method)
	at java.lang.Thread.start(Unknown Source)
	at avf.d(SourceFile:390)
	at avf.a(SourceFile:339)
	at avx.a(SourceFile:274)
	at ave.a(SourceFile:263)

-- Screen render details --
Details:
	Screen name: ave
	Mouse location: Scaled: (343, 174). Absolute: (687, 344)
	Screen size: Scaled: (640, 347). Absolute: (1280, 693). Scale factor of 2
Stacktrace:
	at bet.b(SourceFile:718)
	at atn.S(SourceFile:685)
	at atn.d(SourceFile:618)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.1
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_21, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
	Memory: 95971656 bytes (91 MB) / 162050048 bytes (154 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 32497 (1819832 bytes; 1 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
	Launched Version: 1.6.1
	LWJGL: 2.9.0
	OpenGL: AMD Radeon HD 7730M GL version 4.2.11566 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: nullserver then it crashed. This is the crash report