This info from Who Crashed:

On Fri 8/12/2011 5:00:59 PM GMT your computer crashed
crash dump file: C:\Windows\Minidump\Mini081211-01.dmp
This was probably caused by the following module: aswsnx.sys (aswSnx+0x13154)
Bugcheck code: 0x50 (0xFFFFFFFFD8A5B8DC, 0x0, 0xFFFFFFFF82C3AAB4, 0x2)
Error: PAGE_FAULT_IN_NONPAGED_AREA
file path: C:\Windows\system32\drivers\aswsnx.sys
product: avast! Antivirus System
company: AVAST Software
description: avast! Virtualization Driver
Bug check description: This indicates that invalid system memory has been referenced.
This appears to be a typical software driver bug and is not likely to be caused by a hardware problem.
A third party driver was identified as the probable root cause of this system error. It is suggested you look for an update for the following driver: aswsnx.sys (avast! Virtualization Driver, AVAST Software).
Google query: aswsnx.sys AVAST Software PAGE_FAULT_IN_NONPAGED_AREA