2000xl stopped reading my ZIP drive, HELP!!

Just today I loaded all my stuff from zip to mpc fine. Later on the mpc seems to activate the zip but acts like the disk isn't formatted. This is doin' it to all my zips no matter what. Here are specifics if it matters: Iomega Zip 250, SCSI, MPC 2000xl

internal or external.......My zip was doing the same thing. I had to re install the Os for the Mp.......now its fine. Which Os are you running?