Do a malware check with some malware scanning programs.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
• http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

All in the above post didnt work for me..

I had this same problem which was driving me crazy !! ..I followed some of the suggestions and some seemed to work for a short while.. After a few days i have managed to succeed in stopping the redirects from happening ..what i did was this ..

I installed browser protect add on from the extensions page then i surfed the net for about 15 mins and constantly browsing and searching with google. I then clicked addons -extensions and options on browser protect.. in options you get 4 tabs look through them and you will see the offending search links ..Delete them all and leave only the ones you know are safe.. then browse and you will see you dont get redirected anymore ... check your options if you start to get redirected again and go through the same process and delete the suckers ...

This is the only solution that has really worked for me, malware scans virus scans and all the rest didnt work .. I even deleted firefox re booted and downloaded again only to find it started to redirect to some crappy "alltheweb2 links and some other links i cant remember now..

Give the above a shot it works !.