Quit poking around?

Seriously - Try the new Lacerte Tool Hub https://proconnect.intuit.com/community/help-articles/help/fix-common-problems-and-errors-with-the-l... I would use the FORCE install. I does not do anything to your data, it just does a new clean install of the program. 

If this does not do it, then there may have been a new Windows update causing the issue. Google gives things like https://appuals.com/fix-the-process-cannot-access-the-file-because-it-is-being-used-by-another-proce.../