Domino server intermittently crashing

Greetings all!

I have a Domino 6.5.3 server running under W2K3. I also have GroupShield 5.3 with the latest patch installed also. Ever since we upgraded to 6.5.3 I’ve had the Domino server crash on me twice with a blank, black screen. No error messages or logs. When checking the Domino log I noted that the last task running was related to GroupShield running a scheduled on-demand task which is run every day. I am somewhat worried about these intermittent crashes and from what I’ve read in the posts so far this could be due to GroupShield. Does anyone have any idea as to what could be causing these crashes? Has anyone experienced such crashes before?

TIA

Pierre