Ubuntu – Cannot set monitor to native resolution

problem is similar to so many other users, but solutions found do not work.
Background:
Fresh install of 12.04 (completely updated) on a Fit-PC2 (specs).
Read in several places that the new 3.X kernel that 12.04 runs on has a new psb_gfx driver which supports the gma500 graphics card (poulsbo chipset).
All's pretty much working (there are some glitches which are documented, so I won't raise them here), except for the screen resolution. My native monitor resolution is 1920X1080, but all I get is 1024×768.

Output running xrandr:

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768
default connected 1024x768+0+0 0mm x 0mm
   1024x768        0.0* 

Although I read that Ubuntu does not come with an xorg.conf file anymore, I also tried running sudo X :1 -configure, and here's the end of the output:

Number of created screens does not match number of detected devices.
  Configuration failed.

When I look in the xorg.conf.new file created in my home directory, it seems that for some reason X thinks I have two screens. Don't know what to do with that. Ideas anyone?
Thanks for your time.