We have had this problem from tine to time here, on a Appleshare server that we run, with an installed copy of Retrospect Desktop on the server.
This copy of Retrospect 4.3 backs up the main SCSI harddrive to a SCSI DDS-4 tape drive. Its a 36 GB drive and the tapes are 40 compressed, and usually works just fine...
One of the other drives has been running very full, a 20GB, with ~500 KB free. Its not a boot drive, so I wasn't worried about it.
Lately, the machine has been crashing in an odd manner. I usually first notice that registered users on the ASIP server are not allow to connect. (bad password, it claims) Upon checking the actual machine, the finder is really slow, and programs, such as Retrospect fail to execute, usually with just nothing happening. This is usually fixed by rebooting. Sometimes, it requires formatting and reinstalling the OS and ASIP, though this last time I just cragged and dropped Retrospect to another drive and then back again.
I at first thought it was the full HD causing the problem, but the problem persisted after removing that drive.
In conclusion, the reason I think its Retrospect, is that it seems to occur after the back up is finished, in the early hours of the morning, and is noticed as people start to come in, around 8, and try to log on.
Any help would be appreciated.