I've seen this exact problem before on this board but unfortunately the hotfixes (910362 & 918673) that have worked for others haven't solved the problem.
My server is sometimes rebooting when a user logs off and although I've been able to determine which users, they have been random.
Below is the typical Event:
Event Type: Error
Event Source: System Error
Event Category: (102)
Event ID: 1003
Time: 4:30:10 PM
Error code 000000ab, parameter1 0000000e, parameter2 000000b8, parameter3 00000000, parameter4 00000001.
Everything is up to date as far as drivers go. I've had this happen on two different servers whose only similarity is that they're running W2k3 sp1 and Citrix PS4 otherwise they're fairly different regarding hardware.
Here are links to the past 5 minidumps-
Thanks and I look forward to everyone's reply!