http://www.mystartsearch.com/

It isn't technically a virus, it's a browser hijack with adware. There are a few options to remove this sort of thing. First I would try http://www.Malwarebytes.org and if that doesn't remove it, you could try http://www.bitdefender.co.uk/solutions/adware-removal-tool-for-pc.html (which I have not personally used), or http://www.bleepingcomputer.com/download/adwcleaner/