So you can get into windows? It sounds like you might have a virus anyways, better off just formatting and reinstall windows. Have windows delete the C:/Windows (default installation directory) and overwrite that directory. When you do so, it will allow you to have a fresh install of windows, with your whole filetree still in-tact, of course you would have to re-link all your files back or reinstall some programs, but at least you are just killing the Windows folder.