Not very much in touch with HP scanner models and you did say that you have has it running.
In whch case try a full reinstall of software for the scanner again
The check out latest drivers from the HP website.
One point -scanners made during the Win98 era, did not in the main transfer too well to XP.
This is bacuse in addition to the driver issue, scanners have built in hardware to runn scannng/tracking/ lamp and the like- and if the circuit was made for 98[DOS] thay would not recognise NTFS[XP] commands - So if it is an old 'un
it may be time for a new'un