In the PM you sent you said that you ran a scan that found 400+ errors. What is the program that you used to run the scan and what type of errors did it find.
Was it a Virus Scan program, a Registry Scan program, a System Cleaner type of program, was it a program that ran scans before you were fully logged into windows, was it a program that ran scans without you telling it to???
I have no ability to know what damage may have been done without knowing what type of scan was run. Also there are many fake anti-virus and registry scan programs that are in fact viruses, so it could even be that type.