I was about to ping you to see if you had it solved or paved over it.
Only trouble with not knowing what caused "it" and what "it" was means: "it" could bite ya again.
Larry
It did bite me again. I installed the backup image and all was fine. I added the three Kontakt instruments and one Kontakt update (5.7.1) and all was well. With Defender turned off I shut down the computer for the night. The next day the Defender problem back.
So I ran Chkdsk c: and it found no bad sectors or other problems. I ran chkdsk c:/f/r/x and it went to 11% and stayed there for quite awhile. I turned off the monitor, turned it on about 6 hours later and the desktop was up. No chkdsk or chkdsk log! Is this normal if all is OK?