Comment 70 for bug 728745

Here is my nvidia bug report for the 270 (current) nvidia driver. You can do this bug report even thought the display is apparently frozen, but you will see no feedback at all (which is really weird).
To do this, press Ctrl+Alt+t (which invisibly open a terminal window), and wait a few seconds.
Type carefully (as there is no feedback) sudo nvidia-bug-report (enter), wait a few seconds
Type your password and enter

If you want to check the report has been created successfully, type Alt+Print screen+k to kill the x server. The login using Ububtu Classic (no effect) and you should see it in the home folder.