I had the same problem.
Googled it and there are lots of suggestions.
I only use windows for a few programs that don't (probaly could) work with linux mint so decided the easiest way out of it was to update the only machine I use on win to win 10.
The intention was to then go back to 7 but can't be bothered.
It's a known problem which ms don't seem to want to solve - the devil in me thinks it's a way of pushing 10.