It caught me by surprise when i used the nvidia driver with 3d experimental driver.
The problem lies on 2 issue:
1. new kernel mode auto enable high resolution via vga=758, which isnt supported on my asus laptop
2. the xwindows nvidia experimental driver didnt work.
So i got a black screen (not even backlight).
to fix it....
@ the grup screen, key edit (e) to edit on recovery mode
go to the line /boot linux ... (add "nomodeset" at the end)
This shall disable high resolution screen for boot up kernel.
in recovery mode, you may reconfigure your graphic to basic graphic,
then relaunch x windows. Inside there, click on additional driver, and disable the experimental driver.
Finally, reboot ;)