Our Win2000 server got a similar problem with SEp 11.00. One day after instalation some of our server shut down it self. Event viewer just inform that the previous system shut down at xx:xx on dd/mm/yy was unexpected.
I found once that the system has terminated a system process "SERVICES.EXE ..... " so then the system restart with count down time.
There is an article for SEP 10 "Blue screen with "STOP 0x0000007f" error on Windows 2003/XP/2000/NT"
found on
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2002071208532048.
My machine doesn't goes blue screen, just restarting with count down time.
I haven't try to modify Registry value as recomended because I can't find any key mentioned in that article. The registry key is
HKEY_LOCAL_MACHINE\SOFTWARE\INTEL\LANDesk\VirusProtect6\CurrentVersion\Storages\Filesystem\RealTimeScan