There is a very good chance that you are seeing the effects of a hijackware infection!
NB: If you had no anti-virus application installed or the subscription had expired *when the machine first got infected* and/or your subscription has since expired and/or the machine's not been kept fully-patched at Windows Update, don't waste your time
with any of the below: Format & reinstall Windows. A Repair Install will NOT help!
Microsoft PCSafety provides home users (only) with no-charge support in dealing with malware infections such as viruses, spyware (including unwanted software), and adware.
https://support.microsoft.com/oas/default.aspx?&prid=7552&st=1
Also available via the Consumer Security Support home page:
https://consumersecuritysupport.microsoft.com/
Otherwise...
1. See if you can download/run the MSRT manually:
http://www.microsoft.com/security/malwareremove/default.mspx
NB: Run the FULL scan, not the QUICK scan! You may need to download the MSRT on a non-infected machine, then transfer MRT.EXE to the infected machine and rename it to SCAN.EXE before running it.
2a. WinXP => Run the Windows Live Safety Center's 'Protection' scan (only!) in Safe Mode with Networking, if need be:
http://onecare.live.com/site/en-us/center/howsafe.htm
2b. Vista or Win7=> Run this scan instead:
http://onecare.live.com/site/en-us/center/whatsnew.htm
3. Now run a thorough check for hijackware, including posting requested logs in an appropriate forum, not here. DO NOT SKIP THIS STEP!!
Checking for/Help with Hijackware:
• http://mvps.org/winhelp2002/unwanted.htm
• http://inetexplorer.mvps.org/tshoot.html
• http://www.mvps.org/sramesh2k/Malware_Defence.htm
•
http://www.elephantboycomputers.com/page2.html#Removing_Malware
**Chances are you will need to seek expert assistance in
http://spywarehammer.com/simplemachinesforum/index.php?board=10.0,
http://www.spywarewarrior.com/viewforum.php?f=5,
http://www.dslreports.com/forum/cleanup,
http://www.bluetack.co.uk/forums/index.php,
http://aumha.net/viewforum.php?f=30 or other appropriate forums.**
If these procedures look too complex - and there is no shame in admitting this isn't your cup of tea - take the machine to a local, reputable and independent (i.e., not BigBoxStoreUSA or Geek Squad) computer repair shop.
~Robear Dyer (PA Bear) ~ MS MVP (IE, Mail, Security, Windows & Update Services) since 2002 ~ Disclaimer: MS MVPs neither represent nor work for Microsoft