Export and save have stopped working

I may have stumbled upon something that could be related to the program not exporting or re-saving scores after I have finished editing. The program has crashed several times and I believe each time has been when trying to change the tempo. I play and record in one tempo, but when the midi file is opened in Musescore it is always a different tempo so the first thing I do is change the tempo to the tempo I played in. 98% of the time it's not a problem, but 2% of the time the program crashes during the process. I believe it is after the crash that the export function stops working. The last 2 times after a crash I had to uninstall and reinstall the program. Today export still does not work after re-installing the program so I am completely without the ability to save and export to midi my editing. Before that I think restarting my computer fixed it, but no longer. Do you have any knowledge of similar problems (both crashing during tempo change and/or not being able to export)? Thank you.