Thanks, DavidR, but I may not have to do that. I went to the quarantined file in the chest and re-scanned it. In the detailed report it showed that of the many, many files in the setup, only two were flagged as "Win32:Adware-gen [Adw]" -- they were both associated with something called the "Alot toolbar." McAfee Site Advisor, and just about everyone else I found on the web, flags this as spyware/adware.
I'll try to follow your directions and run this through Virus Total later, when I have a bit more time, but this looks like the cause. Thank you very much.