Open CMD (command prompt), type "chkdsk" it will do a 3 stage check for window file errors and HDD bad sectors. When done it my ask to press letter key "y" = yes when restart do a disk check and repair......or letter key "n"= no don't do a check when PC boots next time. Before pressing your desired letter key check if any bad sectors is detected, since cmd displays on black screen in basic font in a cramped display, so check properly. If bad sectors detected, you can schedule a disk check on reboot but before doing so get ready to backup your stuff. Its possible you can have bad sectors with virus infections, a choice must be made, to update antivirus and scan, remove infection and then backup. Choice is yours since a failing drive...