Go here
http://www.download.com/Malwarebytes...-10804572.html
download and install this software - its spyware free and will remove the majority of problems from your pc. Once thats done, go here .....
http://housecall.trendmicro.com/uk/
Download and install the ActiveX control if you need it and then install the software and run this online anti virus scan. It will pick up anything that your installed AV/Antispyware software has missed as it checks your computer over the internet.
Do that then get back if its still a problem.