Great--So--we need to triage amongst the add-ons to see which one is causing
this nasty effect.
In IE:
Tools, Internet Options, Programs tab
click "Manage add-ons"
Go through the list here, looking at Name and Publisher for stuff you at
least vaguely recognize...
Not showing a publisher is not necessarily "bad."
(for example, Microsoft has a legit add on whose name is "Research" and
which shows no publisher.)
At the lower left there are buttons for enable/disable. If you come to one
you think might be a candidate for the bad actor, try disabling it. This is
a reversable action--you just come back here and enable it again--so if you
guess wrong and disable the Google toolbar you use every 5 minutes, it is
easy to fix.
I'm looking at IE6 on Vista, so I'm not sure if you have all the same
choices. At the top of the "Manage add-ons" window is a choice of what is
shown--you could choose "add-ons currently loaded in IE"--which is probably
a shorter list and should include the bad guy.
If the bad guy turns out to be an ActiveX control, you can delete it (once
you are sure you have the right critter) via the delete button.
The traditional way to do this kind of work is to download an app which
enumerates all the places Spyware can attach to your system, and creates a
text log file. You then post this log in a moderated third-party forum
where the folks reading the messages are trained to deal with these logs.
But lets see if we can get this cleared up on a more informal basis--this
one may not be so entrenched