what does this mean?

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

Minecraft has stopped running because it encountered a problem.

If you wish to report this, please copy this entire text and email it to support @ mojang.com.
Please include a description of what you did when the error occured.



--- BEGIN ERROR REPORT a1dce528 --------
Generated 12/30/11 10:35 PM

Minecraft: Minecraft 1.0.0
OS: Windows 7 (x86) version 6.1
Java: 1.6.0_30, Sun Microsystems Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
[failed to get system properties (java.lang.NullPointerException)]

org.lwjgl.LWJGLException: Could not create context
at org.lwjgl.opengl.WindowsContextImplementation.nCreate(Native Method)
at org.lwjgl.opengl.WindowsContextImplementation.create(WindowsContextImplementation.java:50)
at org.lwjgl.opengl.Context.<init>(Context.java:120)
at org.lwjgl.opengl.Display.create(Display.java:858)
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:237)
at net.minecraft.client.Minecraft.run(SourceFile:644)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 55cae188 ----------