I say download a good ass anti-virus program (dont ask which one these other dudes can tell u better than I could), but if all else fails, just reinstall windows. When u put the disc in to boot it straight from the disc it'll tell u there is already a version of windows running on the drive, then it'll ask u to either switch drives or format the current drive and reinstall, just format it and reinstall and you got a new computer again. Just save all your shit to a disc or different hard drive before you do that cuz it will delete it all. Hope this can be useful.