It appears you’ve been infected by a variant of the VX2 program. Microsoft documents this specific problem here, and its advice is to run Microsoft AntiSpyware (Beta) - you can download this from here - because this will detect the malicious software and remove it for you. After installation, run a full system scan and MS AntiSpyware will do its job.
You’re not quite finished, though. You’ll also need a re-register a DLL. Click Start > Run, type regsvr32 initpkl.dll and then click OK. Restart your PC and all should be fine again.