No clue really. Just started up the game from the welcome screen and before the game had a chance to start, it crashed. Below is the report that was generated. I hope it helps you figure out where the problem is.

---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 7/31/13 2:20 AM
Description: Initializing game

java.lang.RuntimeException: org.lwjgl.LWJGLException: X Error - disp: 0x7fce6c46d400 serial: 159 error: GLXBadRenderRequest request_code: 154 minor_code: 1
at org.lwjgl.opengl.Display.update(Display.java:648)
at org.lwjgl.opengl.Display.update(Display.java:628)
at ats.R(SourceFile:506)
at ats.O(SourceFile:326)
at ats.d(SourceFile:599)
at net.minecraft.client.main.Main.main(SourceFile:101)
Caused by: org.lwjgl.LWJGLException: X Error - disp: 0x7fce6c46d400 serial: 159 error: GLXBadRenderRequest request_code: 154 minor_code: 1
at org.lwjgl.opengl.LinuxDisplay.globalErrorHandler(LinuxDisplay.java:318)
at org.lwjgl.opengl.LinuxContextImplementation.nSwapBuffers(Native Method)
at org.lwjgl.opengl.LinuxContextImplementation.swapBuffers(LinuxContextImplementation.java:79)
at org.lwjgl.opengl.ContextGL.swapBuffers(ContextGL.java:175)
at org.lwjgl.opengl.DrawableGL.swapBuffers(DrawableGL.java:90)
at org.lwjgl.opengl.Display.swapBuffers(Display.java:618)
at org.lwjgl.opengl.Display.update(Display.java:646)
... 5 more

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

– Head –
Stacktrace:
at org.lwjgl.opengl.Display.update(Display.java:648)
at org.lwjgl.opengl.Display.update(Display.java:628)
at ats.R(SourceFile:506)
at ats.O(SourceFile:326)

– Initialization –
Details:
Stacktrace:
at ats.d(SourceFile:599)
at net.minecraft.client.main.Main.main(SourceFile:101)

– System Details –
Details:
Minecraft Version: 1.6.2
Operating System: Linux (amd64) version 3.8.0-19-generic
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 99507736 bytes (94 MB) / 145883136 bytes (139 MB) up to 954466304 bytes (910 MB)
JVM Flags: 1 total; -Xmx1G
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.6.2
LWJGL: 2.9.0
OpenGL: Gallium 0.4 on AMD ARUBA GL version 1.4 (3.0 Mesa 9.1.3), X.Org
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: ~_ERROR~ NullPointerException: null