Other than the SYSTEM_SERVICE_EXCEPTION due to gdrv.sys (which I am not seeing any more) the crashes have been related to the following:
==================================================
Dump File : 022213-17487-01.dmp
Crash Time : 2/22/2013 10:23:34 AM
Bug Check String : DRIVER_PAGE_FAULT_IN_FREED_SPECIAL_POOL
Bug Check Code : 0x000000d5
Parameter 1 : fffff980`02f26e40
Parameter 2 : 00000000`00000000
Parameter 3 : fffff880`04dc81aa
Parameter 4 : 00000000`00000000
Caused By
Driver : ntoskrnl.exe
Caused By Address : ntoskrnl.exe+75c40
File Description : NT Kernel & System
Product Name : Microsoft® Windows® Operating System
Company : Microsoft Corporation
File Version : 6.1.7601.18044 (win7sp1_gdr.130104-1431)
Processor : x64
Crash Address : ntoskrnl.exe+75c40
Stack Address 1 :
Stack Address 2 :
Stack Address 3 :
Computer Name :
Full Path : C:\Windows\Minidump\022213-17487-01.dmp
Processors Count : 8
Major Version : 15
Minor Version : 7601
Dump File Size : 270,616
==================================================