How do I get a driver selection to 'stick'?

Here's my video card:

00:02.0 VGA compatible controller: Intel Corporation 82915G/GV/910GL Integrated Graphics Controller (rev 04) (prog-if 00 [VGA])

I go to System -> Administration -> Screens and Graphics.

I select either the "intel" or the "i810" driver via "Choose driver by name" and press "Test". My screen goes black and then grey and a dialog box asks me to choose between "Cancel" and "Keep current configuration". I choose "Keep current configuration". I then press "OK" and displayconfig-gtk closes down.

As soon as I re-open it, "vesa" is selected again.

A similar thing happens selecting a monitor. I try to choose "LCD Panel 1280x1024" (as given by get-edid), I test it, I choose "Keep current configuration", but if I press "OK" and launch displayconfig-gtk again, it's gone back to Plug and Play, 800x600.