Pop Ups / dialog boxes do not display
All pop up windows such as the start center, or instruments window will not appear. For example, when I go to open the Instruments window, the screen fades a little, as if there is a new window, however nothing appears. Because Musescore thinks a window is open, I'm not allowed to click anywhere on the screen, so I must go to take manager and close Musescore.
Comments
Most likely your monitor configuration has changed since hte last time you opened those windows, and MuseScore is trying to open them at the same location as they were displayed last time but that location no longer exists (eg, a second monitor was attached then but is not now, or there was a drastic reduction in resolution). Help / Revert to Factory Settings will fix that.
If you continue to have problems, please use the Support forum to ask for help in using MuseScore, not the issue tracker.