Guest JTT,
Your first mistake was buying a zip drive. You'll be in store for this sooner than later. I would suggest that if this was recent purchase you run (not walk) back to the store where you purchased it from and get a full refund. Consider a CD burner instead. 650 megs of storage on a blank CD for under 2 dollars as opposed to 100 megs of storage for 12-15 dollars for a zip disk...and the dreaded "click of death" to have to contend with. There is a very large class action suit currently in progress against IOMEGA.

Remove the zip drive from your computer. Go into Device Manager, and remove from there as well in Disk Drives.

Go into Accessories-->System Tools-->System Information and restore all your driver and configuration files as they were before you installed the zip drive.

If this doesn't solve the problems you're experiencing, then a complete reformatting of the hardrive, and reinstallation of Windows is the only rememdy.