Cubase freezes when opening drop-down

Cubase freezes completely when trying to open any drop-down menu.

This started happening after I tried the 10.5 trial version. Both Pro 10 and Pro 10.5 did this almost every time (bot not every time), in any project, no matter the size or complexity.

I removed both version of Cubase and reinstalled 10. Still, the problem persists.
Task manager can’t shut down Cubase when this happens. But hitting the windows-key, thereby opening the start menu, wakes Cubase back up from the dead - until I try to open a drop-down menu again, that is.

I have done all the classic audio-optimizing of windows (shut off USB-power-control etc.), all drivers are up to date, and I tried rolling back the last few windows updates. Nothing seems to have any effect at all.

Intel Core i7-6700, 3.40GHz, 4 cores
Windows 10 Pro

Any ideas?
I’ve made this small video showing what it looks like:


Could you try in Cubase Safe Start Mode, please?