Thank you all very much... it seems there are one or two more things to try that won't require a sleeping bag and multiple pizza deliveries to get through. I am going to try several of these one at a time (I want to know what solved the problem - if that happens) and will report back on success or lack thereof.
I will try...
1 ...try adding the offending site to your hosts file
2 ...block access to the site via firewall or IE monitoring software... (thank you for your interest and suggestions OverdueSpy, although I would guess you have an interest in what is going on with that domain/IP address just for its own sake - who says self-interest is incompatible with the greater good?)
3 Ad-Aware
4 wintasks 4 and hijack this
5 1. Spyware Guide, 2. Spyware Info
6 http://toolbar.google.com/
7 FORMAT THE HARD DRIVE AND RUN FOR THE HILLS!!!! (the hills are alive, and it's kind of scary)

...and that's ok Boogymantroy - it can be hard to follow everything when people write REALLY LONG entries (iankestor?)