First eliminate any spyware.
What You Should Know About Spyware
http://www.microsoft.com/athome/security/spyware/devioussoftware.mspx

CAUTION!!!!!  Before you try to remove spyware using any of these programs ,
download a copy of LSPFIX from any of the following sites:
http://www.cexx.org/lspfix.htm
http://www.spychecker.com/program/winsockxpfix.html
(if your OS is Win2k or XP) The process of removing certain malware may kill
your internet connection. If this should occur, this program, LSPFIX, will
enable you to regain your connection.

See
Dealing with Unwanted Malware, Parasites, Toolbars and Search Engines
http://mvps.org/winhelp2002/unwanted.htm

Note that AdAware and SpyBot S & D will each catch some things the other
won't.  Also, each needs to be updated with the program's update function
before every use, even when just downloaded.  There's also a lot more to do
than just those two programs.  CWShredder is also available here:
http://www.intermute.com/products/cwshredder
**Post your HijackThis log to
http://www.spywareinfo.com/forums/
http://forums.tomcoyote.org/
http://castlecops.com/forum67.html
http://www.wilderssecurity.com/ or the Spyware forum at
http://forum.aumha.org/viewforum.php?f=30 for expert analysis, not here.**
Alternative download pages for Ad-Aware, Spybot, HijackThis and CWShredder
may be found on this page:
http://aumha.org/a/parasite.htm.

See this link for information about malware:
http://arstechnica.com/articles/paedia/malware.ars

If nothing there helps, please post back to this thread.