My Minecraft all of a sudden crashed. Need help. I have the latest version of Minecraft.

Minecraft has crashed!
----------------------

Minecraft has stopped running because it encountered a problem.

--- BEGIN ERROR REPORT 7cf3a456 --------
Generated 3/18/12 8:16 PM

Minecraft: Minecraft 1.2.3
OS: Linux (amd64) version 2.6.38-8-generic
Java: 1.6.0_26, Sun Microsystems Inc.
VM: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
[failed to get system properties (java.lang.NullPointerException)]

org.lwjgl.LWJGLException: Could not init GLX
at org.lwjgl.opengl.LinuxDisplayPeerInfo.initDefaultPeerInfo(Native Method)
at org.lwjgl.opengl.LinuxDisplayPeerInfo.<init>(LinuxDisplayPeerInfo.java:52)
at org.lwjgl.opengl.LinuxDisplay.createPeerInfo(LinuxDisplay.java:684)
at org.lwjgl.opengl.Display.create(Display.java:854)
at org.lwjgl.opengl.Display.create(Display.java:784)
at org.lwjgl.opengl.Display.create(Display.java:765)
at net.minecraft.client.Minecraft.a(SourceFile:230)
at net.minecraft.client.Minecraft.run(SourceFile:650)
at java.lang.Thread.run(Thread.java:662)
--- END ERROR REPORT 309235fb ----------