same problem, I’ve been working on my projects for months with no issues, same version from the beginning, last week I launched the projects multiple times and It freezes my PC and I have to restart it manually.
a few things I tested:
1-as long as I don’t click on the project window while it’s launched it doesn’t crash but it runs slowly in "out of focus mode"
2-when I open 2 projects at the same time, and alt tab back to back when one of them is freezing, it “cancels” the freeze.
3-it does the same thing with brand new projects (so it’s not liked to my project in particular)
4-it does this on version 4.20 , 4.24 , 4.25 , 4.26
5-I disabled smart screen, reinstalled graphics drivers, checked on DX12, etc… everything seems in order, I will soon look into the hardware side of things.