[ubuntu-uk] Display resolution

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I have an old Dell Latitude D600 and since a recent update, the maximum screen 
resolution I can select is 800x600. Card and display details are:
*******************
jbrid at jbrid-Latitude-D600:~$ lspci | grep VGA
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon RV250 [Mobility 
FireGL 9000] (rev 02)
jbrid at jbrid-Latitude-D600:~$ xrandr
Screen 0: minimum 320 x 200, current 800 x 600, maximum 4096 x 4096
VGA-0 disconnected (normal left inverted right x axis y axis)
DVI-0 disconnected (normal left inverted right x axis y axis)
LVDS connected 800x600+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0 +   60.0  
   1360x768       59.8  
   800x600        60.3*    59.9  
   848x480        59.7  
   720x480        59.7  
   640x480        59.9     59.4  
S-video connected 800x600+0+0 (normal left inverted right x axis y axis) 0mm x 
0mm
   800x600        59.9*+
   640x480        59.9  
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Anyone have any ideas how I can get it to revert back to 1024x768?

Thanks

John