This may be caused by spyware/malware that's gotten installed on
your system. Use Ad-Aware and/or Spybot Search & Destroy to remove it.
Ad-Aware:
http://www.lavasoftusa.com/ (but I see you've already tried this
one)
Spybot:
http://security.kolla.de/
Good sites on how to install and use Spybot -
http://www.net-integration.net/reviews/spybot1.html
http://tomcoyote.com/SPYBOT/index1.php
More information here:
http://www.spywareinfo.com/
http://www.mvps.org/inetexplorer/Darnit.htm
http://www.doxdesk.com/parasite/ - runs a little script when loading page to
check for common parasites
If no joy, in IE go to Tools...Internet Options...Advanced tab, Browsing
section, uncheck "Enable third-party browser extensions", click Apply, click
Okay, reboot. If that solves your problem, then more troubleshooting is
needed to find out exactly which program, or Browser Helper Object (BHO) is
causing this problem. You don't want to leave it at that, as some BHOs are
useful or necessary - like Adobe Acrobat for reading .pdf files or an
essential component of Norton AV. Get BHODemon -
http://www.definitivesolutions.com/bhodemon.htm - read all about BHOs.
Disable all items, and then gradually replace one or two at a time to narrow
down the culprit.
If all the above fails, then the problem could be something new that the
spyware cleaners above don't have in their databases yet. In that case....
HijackThis direct download:
http://209.133.47.200/~merijn/files/HijackThis.exe
Tutorial on how to use HijackThis:
http://www.spywareinfo.com/~merijn/htlogtutorial.html
Then post it's output log to the forum here for analysis and feedback by the
parasite experts:
http://www.spywareinfo.com/forums/
Or the other HijackThis Logs forums listed here:
http://www.spywareinfo.com/~merijn/forums.html
Or try this program to get some of the most nasty malware:
CWShredder direct download:
http://aumha.org/downloads/cwshredder.zip
An alternate resource for all of this and more:
http://www.aumha.org/secure.htm
More info on how to get your search back in order after cleanup:
http://inetexplorer.mvps.org/answers4.htm#search_engine