Well you can stop at the sfc is failing.
Honestly, your quickest fix is likely a repair install, since the system is bootable it will be the least involved method.
You will require a windows 7 disc to do this. Repair Install
If sfc is failing you have data failing the hash check, which means window's system files are corrupt or somehow vary from how they are supposed to be.
A future note, registry cleaners ...and anyone that has time helping on this site will tell you this, cause far more problems than they solve with windows 7.