You might have to bite a money bullet and purchase a trueblue MS or OEM Windows 7 or 10 install DVD -- if push comes to shove. If you find out that the hardware, i.e. the HD, is aok, then the Windows has suffered an almost impossible to fix failure. A MS or OEM install DVD will give you a fresh install, a start over from scratch install. You might be able, using another pc, to download an ISO that matches your present Windows edition and go from there.
Did you run system file checker from cmd?
sfc /scannow
Did you try resetting Winsock?
CMD open as admin
type
netsh winsock reset
restart computer
Thanks for those suggestions, Snick! Just did them both.
Unfortunately, I still get the "Could not connect to System Event Notification Service", followed by a black screen, when trying to log in after startup.
When I try to do another system restore (to regress the system to its pre Dec 19th state), I get that same error message: "Windows has detected file corruption on local Disk C. You must check the disk for errors before it can be restored." (This despite countless disk checks!)
The annoying thing is that the system appeared to work fine (and was at least fully useable) until Windows forced that auto-update on December 19th!
Quote