Jaz drives use removable media, which can have its drawbacks in certain cases. The main problem with removable media drives is that they can allow contamination, in the form of dust, to enter into the drive mechanism. Any contamination can cause serious problems with your data. If the errors only occur with that particular Jaz cartridge then the problem is probably limited to that cartridge only and you should discard that cartridge. (Hopefully you have all of the data backed-up!) If you are unable to ready ANY disks with your drive, more than likely you have a defective drive and you should seek out an Authorized Service Center to correct the situation.