I had this same problem. I switched back to nouveau drivers for my Nvidia card, instead of the proprietary drivers, and everything works perfectly. I also seem to be getting better overall performance in day-to-day desktop activities and battery life. I don't really do anything that needs 3d other than the desktop compositor.

When I was using he non-open-source drivers, Ctrl-Alt-F# to change virtual terminals would sometimes help. I would switch to a random virtual terminal and back and sometimes it would be working again.