AAR81xx1 - server 2003 R2 keeps freezing

Hi all experts - I'm danish but writing in english since this seems to be a quite rare problem - and then people outside Denmark could also benefit from your inputs. However - feel free to respond in danish if you like, then I will make an english summary later.

The screen on my windows Server 2003 R2 keeps freezing, now and then the server crashes altogether, I have not installed any new drivers or updated any drivers, but when I look in the event records the error is SCSI/AAR81xx1 Event ID 9.

The text above is copied from the internet and describes exactly the problem. However i cannot find a solution so now I post the question on Eksperten.dk.

The server is a Supermicro with a raid installed. We also have LogMeIn running for remote access.

Lately it just freezes and we can get less and less contact with it. Keyboard and mouse suddenly dont work anymore but sometimes we know theres still some activity going on inside the server - some databases keeps responding. But we normally have to cut the power to get the server to restart. It doesnt seem that the server is heavy loaded in memory.

When using BurnIn Test Pro to test hardware there are no problems reported. The problem occured even when we have disabled Windows update on the server and didn't install new software. we now updated the server 100% with updates but the problem still occurs.

We also have an UPS for cleaning power "in front" of the server but sometimes we also have a message saying "battery is low"...!! This is even that we do have the UPS on and at the server dont have any batteries installed (its a big server just plugged in).

Other software: Kaspersky antivirus.
Virtual PC for running an extra image (problems occurs even when VirtualPC has been closed)
The server is a databaseserver running some quite big databases
The problem has been reported on the internet but no real solutions has been reported.

I hope somebody knows a solution