Почему у меня когда устанавливаю hd-pack когда захожу пишет следующее:

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 12.09.12 14:06

Minecraft: Minecraft Beta 1.7.2
OS: Windows 7 (amd64) version 6.1
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
OpenGL: GeForce GTX 550 Ti/PCI/SSE2 version 4.1.0, NVIDIA Corporation

java.lang.NullPointerException
at net.minecraft.C.fbb.‹init›(Unknown Source)
at net.minecraft.client.Minecraft.J(Unknown Source)
at net.minecraft.client.Minecraft.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT e553c981 ----------