When did this begin happening? What have you changed since then? Have you added any hardware or software to the system? Have you updated or upgraded any software in the system? What system are you using? Is the drive appearing in My Computer, and you are just unable to access it, or is the drive itself not showing up at all?

Another thing to check is to go to START | SETTINGS | CONTROL PANEL | SYSTEM | PERFORMANCE. Make sure that about half way down this screen, Windows indicates it is "configured for optimal performance." If it does not, and you have a white box with information in it, what exactly does this white box say?

I have been unable to access since yesterday. I haven't changed or added anything. . .no updates or upgrades. The drive does appear in My Computer and each time I attempt to access the error message "E:/ is not accessible. The device is not ready"appears.

SYSTEM indicates "configured for optimal performance."

I've deinstalled, removed & checked all connections,
reinstalled, and still it's unaccessible.

Does it do this for all Zip disks you try to access? If you use a blank Zip disk in the drive, can you format it using the Iomega Tools? How is the Zip drive connected to the computer? If it is attached to the parallel port, is it the only device connected? If not, remove any other devices, and connect the drive directly to the computer. Can you access a Zip disk now?