Thanks to Bruce McKee and Noam Rathaus for the tip: Microsoft has released a new hot-fix for Windows NT 4.0 Service Pack 3 that fixes a problem with ATAPI ZIP drives. If you are using a Parallel of SCSI ZIP drive, this fix is not for you! The problem is that Windows NT identifies the ATAPI version of the Iomega ZIP drive as a floppy disk drive and assigns it the first available floppy disk drive letter (usually B). Windows NT then refuses to access the drive. You can download the hot-fix from the Microsoft FTP site