Problem: CPx and HP PSC 500

I've been working on this problem for several days and am about to give up hope of finding a solution.  It's for a friend of mine who recently purchased a used Latitude CPx (and docking station) with Win2k as a replacement for his desktop pc with Win98.  He has an HP all-in-one PSC 500 that, up until the computer swap, was working fine.  Through many trials and tribulations, I've been able to get it to print from Win2k successfully.  Unfortunately, when trying to scan something, it errors out stating it can't communicate with the device.  I've spent many hours searching the Internet for information and have used several suggestions that I've found, but to no avail.  I've tried changing the BIOS and Windows settings for the parallel port (ECP vs. Bi-directional)...I've completely uninstalled and reinstalled the drivers (even to the point of manually clearing entries in the registry)...I've disconnected and reconnected that thing more times than you can shake a stick at.  At this point, I'm beginning to think there's a hardware incompatibility issue between the laptop and the scanning portion of the device.  Is that possible?  I've thought about upgrading him to WinXP; but am afraid it might waste his money if this is indeed a hardware issue.  Any help would be GREATLY appreciated.  Thank you!