64 bit - 12.04.2 Nvidia driver issue?

I just installed 12.04.2 and I'm stuck with 1024x768 resolution on my GTX560.

Impossible to change the resolution; the native resolution (1680x1050) is not detected.
Any clue ?
Thanks.

The additional drivers panel doesn't show any driver to install, so I kept the original driver.
Here is the xrandr output anyway:

Screen 0: minimum 8 x 8, current 1024 x 768, maximum 16384 x 16384
DVI-I-0 disconnected (normal left inverted right x axis y axis)
DVI-I-1 disconnected (normal left inverted right x axis y axis)
DVI-I-2 connected 1024x768+0+0 (normal left inverted right x axis y axis) 430mm x 270mm

   1024x768       75.0*+   60.0  
   800x600        75.0     60.3  
   640x480        75.0     59.9  
HDMI-0 disconnected (normal left inverted right x axis y axis)
DVI-I-3 disconnected (normal left inverted right x axis y axis)