I have solved my problem.

At least I’ve solved it to my satisfaction … sort of.

I made my husband an Administrator also. As soon as I did that, I was able to run AVAST from his desktop.

I was able to do that “extra” file check from the folder I’ve added to his desktop for checking attachments that come in emails.

Regarding my computer. XP was on it when I bought it new. It is not something I’ve added.

I did do a clean install a couple of months ago (heaven only knows if I did that right … everything seems to work).

I am an NTFS.