Try running System Restore in Safe Mode.
Reboot your computer and keep tapping the F8 key until the menu appears.
Select Safe Mode with Networking
Once the computer has booted up, run the system restore - select a restore point prior to the time you noticed the problem.
Allow the system restore operation to run and see what happens.
The only caveat with running System Restore in Safe Mode is you will NOT have the option to “undo” the operation because system restore does not create an “undo” point when run in Safe Mode.
I have run System Restore in Safe Mode in the past and it has saved my a** on more than one occasion.
Give it a try and let us know your results.