The same problem happen to me. I tried lots of reinstallation of the official and unofficial driver.
It's all my fault :) I wanted to build my own driver module ...
Finally, bored, I've done some hard cleaning :
CARE ! this solution worked for me cause my ubuntu didn't load the right module (nvidia rather than nvidia_new) but it's quite messy to remove the modules as I've done.
Maybe it's not the best solution but it worked...
The same problem happen to me. I tried lots of reinstallation of the official and unofficial driver.
It's all my fault :) I wanted to build my own driver module ...
Finally, bored, I've done some hard cleaning :
sudo rm -f /lib/module/ [currentkernel] /volatile/ nvidia. ko [currentkernel] /volatile/ nvidia_ legacy. ko
sudo rm -f /lib/module/
CARE ! this solution worked for me cause my ubuntu didn't load the right module (nvidia rather than nvidia_new) but it's quite messy to remove the modules as I've done.
Maybe it's not the best solution but it worked...