Exactly, Kermit! Sorry if I didn't make myself clear, PA Bear.

Until recently, I ran Spybot S&D (with its Immunization feature invoked).

When I upgraded to IE8 and ran into problems, I disabled Spybot S&D's
Immunization feature and cleaned out my Restricted Sites zone (using
DelDomians)

When Dan suggested it, I took his advise and ran a one-time, on-demand
Spybot S&D scan (with the Immunization feature still disabled) and the scan
found nothing -- which is what the other malware scans that I previously ran
also found.