I've had exactly the same problem described above. Installed Nvidia drivers via via Additional Drivers and all was working fine.
After that I decided to remove the Nvidia drivers and rebooted the laptop. My screen resolution was set as 640x480, without any possibility of changing it.
Asking for help, on #ubuntu+1 @ Freenode, someone told me to check /etc/modprobe.d for a nvidia conf file. I've done that and it was there.
Deleting the file and rebooting the laptop solved the issue.
I've had exactly the same problem described above. Installed Nvidia drivers via via Additional Drivers and all was working fine.
After that I decided to remove the Nvidia drivers and rebooted the laptop. My screen resolution was set as 640x480, without any possibility of changing it.
Asking for help, on #ubuntu+1 @ Freenode, someone told me to check /etc/modprobe.d for a nvidia conf file. I've done that and it was there.
Deleting the file and rebooting the laptop solved the issue.
Exterminador