This sounds like adware. Google for "Spybot" and "Lavasoft" (both free for personal use), install, update and run. If they don't work there are other possible removal options.
Another 2 I know of that you can use to attempt to get rid of scumware are http://www.emsisoft.com/en/software/free/ (A squared free) and http://www.ewido.net/en/ (Ewido) - download the trial version - it will revert to the free version at the end of the trial period. In both cases dont forget to update before scanning - both have internal updaters.