Crash upon startup (Win64, MuseScore-3.6.2.548021803-x86_64.msi)

Hello,
I am encountering difficulties with MuseScore 3: I am unable to start MuseScore 3: crash upon startup, even after un-install, re-install (I tried several times such re-install, with no success)

My LapTop:
Dell Latitude 5480 ; Intel Core i7-7820HQ, CPU @ 2.90GHz; 32,0 Go RAM.
Windows 64 bits, version 21H2, build 19044.2251

I have MuseScore intalled since a long time, and I had switched to MusScore 3 about 2 years ago.
(my MuseScore 2 install is still there and able to start/run OK)

The last 6 month, I experienced very long MuseScore3 startup time (about 1 or 2 minutes!!) .

Now, I get a MuseScore 3 crash at every attempt to start MusScore3.
I even un-installed the program, and then re-installed it:

upon startup, I get the message : "la session précédente a été interrompue; restaurer la session?", with the choice "yes", or "no".
Clicking either "yes" or "no" lead both to a crash: "unfortunately, MuseScore has crashed; would you like to send a report to make it possible for us to fix the problem ?"

HELP!