Our GPU computer crashed the day before yesterday. Since there are multiple users on that machine, I don’t know who made the mess. Anyway, we simply could no longer start gnome. So we ended up reinstalling everything.
This link is helpful. But installation did not work in our case. We had the nasty “low-resolution” problem. The problem was solved if I uninstalled the driver first with envy.
sudo apt-get install envyng-core sudo envyng -t