Sorry about the delay in getting back to you on this...
Anyway, I finally tried Avast! again... This time to my utter surprise it works perfectly!
Only difference is that this time I installed the new release. Possibly not something on the bug list, but whatever happened this release works as it should on Win XP x64.
The only other thing it could be is that this time I stuck with the standard skin. Err, yes I may have forgotten that little bit in my last posts.
I don't think that was the issues, but you just never know...
FYI, that other virus scanner I was using (until Avast was working again) called the task known as scanning your PC "testing"! WTF!
It did work, but never gave me that "warm and fuzzy" felling I get with Avast!.
Anyway, you have one VERY happy camper again!