Well, good news and some bad. Cleaning the motherboard seems to have addressed the disappearing files and folders issue, so I can check that one off the list. The remaining problem appears to be scsi related...my setup includes a ZIP 100 and an Asante Mini EN/SC. When I boot up with the scsi devices attached, about half the time I get no chime and a garbled screen that doesn't clear. After powering down and disconnecting the scsi devices the system works perfectly.

Any suggestions on my next move?