USB port device on notebook running Win

A notebook running Win 98 has the following problem:
1. Connected with an Iomega Zip 250 and has ioware and usb driver installted. Once a file (any type) on this drive is activated, it hangs up the whole system. Error is “Iomega Parallel Port Interface – this device is either not present, not working properly, or does not have all the drivers installed (Code 10)”.
2. Connected to HP Jornada Pocket PC with a USB port, error is “Windows stopped responding while attempting to start this device and therefore will never attempt to start this device again (Code 11).
– Aboves are like USB port related. Any idea what’s wrong or how to approach this trobleshooting ? Thanks.