HP Scanjet 4800 series view problem

I've been trying to help a friend, who scans slides using the
Hewlett-Packard Scanjet 4800 series Photo Scanner. However, after he
scans the slides, no image of them appears in the view window. This is
a recent phenomenon, as it worked perfectly before then.

I tried changing a setting that supposedly tells the program what image
directories will appear in the viewer, but no matter what I select a red
warning appears and the window closes down. I believe the default
directory HP sends the images to is /Desktop/HPPhotoSmart.

I uninstalled the HP software and reinstalled it, but the problem
remains. Anyone know if this is a hardware, software, or setting problem?