Hi Stan,
To check for possible caused of this issue, we advise that you performSFC scan when that scan completes, run this command in CMD "chkdsk c: /f /r " and hit Enter. That command will fail, as Windows cannot check your disc while Windows is running, you will be asked if you want to run check disc at startup, choose yes. Then shut your system down and restart it to run disc check.
Feel free to get back to us if you need further assistance.