If you notice that your browser redirects to a page you did not intend, or your system seems to be running slow, you may be a victim of a Virus or Malware.
I found some good information on another site that tells you how to deal with such problems.
Proper repair of any malware is a 3-step process, using automated tools that are readily downloadable from the Internet.
1. Fix the registry.
2. Kill the rogue processes spawned by the malware.
3. Run the scanner to find/repair/delete the infection.
Links to the tools are:
1. FixNCR.reg (http://download.bleepingcomputer.com/reg/FixNCR.reg)
2. RogueKiller (http://www.sur-la-toile.com/RogueKiller/)
3. Malwarebytes (http://www.malwarebytes.org/)