Crash on startup

When it worked:
1. Double-click desktop icon
2. MuseScore title screen appears
3. Program loads and works.

However, beginning today:
1. Double-click Desktop icon
2. MuseScore title screen appears
3. Small, blank "Play Panel" window appears (WTF?)
4. MicroSoft "Report Problem" screen appears
5. Program closes

I have:
Run MuseScore Uninstall, deleted MuseScoreSetup, gone to web site, reloaded SetUp file, run SetUp. No change. Still get 3 thru 5 above.
Run Revo UnInstaller to delete all MuseScore files, gone to web site, reloaded SetUp file, run SetUp. No change. Still get 3 thru 5 above.

WTF?

Am I the first with this? NOT an honor.