Canon F50 printer/scanner/fax - problem using scanner

I know this isn't quite a printer question, but I'm hoping somebody
here has this printer and knows how to solve this problem.

I just got it used for my parents. Their old fax machine / copier
doesn't work any more, and they've been wanting a scanner as well.

When I ran the setup program, it said it couldn't find any printer
hooked up. I did a few things, and it eventually ran the setup
utility. It did have an error message with one file (I should have
written it down).

Since then, it has printed fine, made copies, and printed directly
from a scan. But when I try to scan via photoshop, it comes up with an
error as soon as I choose preview or scan. The scanner starts to scan,
and then the error comes up. It says a file is missing or corrupt,
reinstall the software. I have tried to reinstall, and it goes back
to the not connected problem and refuses to reinstall.

I need to reinstall it to fix the file problem, but I can't get it to
recognize that it is there, even though it will print just fine from
various programs.

Any suggestions?