I was changing some settings in Windows and it caused my SW2019 SP2 to lock up. The only way to get out, was to mouse down and click on anything in the Windows taskbar.
It would lock up SW when I was in a part > sketch, trying to CTRL select two lines to make them equal (relation).
Make a long story short, it was this setting in Windows (that I had changed earlier in the day):
I'm not sure if this locks up anyone else's, but its very reproducible on my computer:
Dell Precision, Win 10, SW 2019 SP2
I hope this helps,