Hi
If you can login in safe mode, create a new user account (admin)
restart PC and try to loginto the new account
If this suceeds then the original account was corrupted.
Run Chkdsk
run antivirus scans
run anti spyware scans (malwarebytes, super antispyware or similar)
Once you are sure there ar no malware left, access the My Documents folder in old account and take ownership of these files, possibly copying to new account My Documents
carry on with using new account unless old account is now working again
Ideally have one full admin account (for installing new programs) and a restricted account for browsing the internet and a spare full admin account for emergencies like this
This may be quicker than a full Windows install from scratch
regards
Mike Barnes