I have the same problem, windows turn black after a while. It seems to relate to how many windows I have open, and how big those windows are. I can for example get the contents of the window back if I make it smaller in size.
I can also get the contents back of windows if I close a couple of other windows.
However, it's really frustrating not beeing able to use lot's of windows at the same time. It would be awesome if you could fix this bug! Everything else works perfectly!
Maybe it's some buffer or memory that's not big enough, and runs out after a while?
Edit1: Attached nvidia-bug-report.log from my system.