Like roy my 5500 is a SCSI scanner, and having had a "spot of bother" with my W98SE I had to reconfigure several things.
Only today, the scanner, which I thought was working, wasn't and began to think it was time to look for a new one.
I let Windows go through the search for a driver and accepted its failure to do so. This brings up yellow warnings in device manager but only when the scanner is connected.
Then I uninstalled the Epson scanner software.
Rebooted at every stage.
Reinstalled the scanner driver (Epson CD) and ran the Epson Test which worked fine. Still my Corel Photopaint complained that it couldn't open the Twain, or that the scanner wasn't connected............Shut it all down because I had to go out for the rest of the morning, and Hey this afternoon it is working, back to normal and no fuss..........I hope you get there quickly.