REMOVING MALWARE/VIRUSES/SPYWARE:
Download and install the free version of Malwarebtyes anti-malware its a very effective malware remover, once installed update it and run a quick scan, remove anything it finds.
http://www.malwarebytes.com
If you downloaded but are unable to install Malwarebytes its likely the malware on your computer is blocking it in some way, try renaming mbam.exe to a random string of letters or numbers as the malware may be designed to block mbam.exe.
If you are still unable to install or download Malwarebytes try Hitman Pro its far less likely to be blocked, it scans with 5 different anti-virus engines at once, simply activate the 30 day free trial once you PC is clean remove it, if you are unable to get to either of the websites please email me for advanced instructions on how to check your "hosts" file and device manager for malware.
http://www.surfright.nl/en/hitmanpro
If you haven't got real-time anti-virus software installed on your PC id recommend installing Avast, its free and as effective as paid for software.
http://www.avast.com
CNET Review and user reviews:
http://download.cnet.com/Avast-Free-Antivirus/3000-2239_4-10019223.html