Mike -----Thanks for the advice--tried it and got the same result--and again, only 30% of my files were actually scanned. The other suggestion I have had, is to remove both McAfee and Zone Alarm from my PC and install new AV / Firewall protection. I am a little reticent to do this--seems a bit drastic--but if no viable solution to the problem can be found, it may be the only option.
PS Even as I write, another auto-download is being attempted--again to no avail.