Cannot access Zip Disk

Hi,
I have a user that is unable to read Zip disks. As far as I know…nothing new has been done to the laptop. The drive is there and Windows recognizes it as a Zip Drive. However when you try to open it, I get a disk not accessable. I tried 3 newdisks, swapped out the drive and the cable. Reinstalled the latest drivers for NT from Iomega (twice); still nothing. The event log is showing “AIC78xx failed to start. Does anyone have a clue?