No Scanner Attached!

I hav a Canon 8400F scanner installed on Vista Ult. using Canon drivers.
When I try to use Windows Fax and Scan the program says there's no scanner
attached yet when I test it in Vista it passes with no problem. It also
scans just fine using PaperPort. Any suggestions?

I have the same with my very very old HP SJ5P scanner that is running
fine using the old HP Deskscan 2.9 software because it uses TWAIN to
talk to the scanner -- but Fax & Scan says it can't find a scanner.

That doesn't bother me since I don't fax from the PC