Download your latest graphics card
drivers and if applicable monitor display drivers
ATI/AMD Graphics Drivers & Software Envision Website > America > Support > Drivers (Left) > LCD Monitor
If that doesn't help, here is a potential fix.

Warning
This is registry edit, backup your registry before attempting this.
Quote:
1) Go to Start --> Run --> regedit and press enter
2) Click 'Edit' and click 'Find' in the Edit menu
3) Type ' DefaultSettings.XResolution ' (without quotes) and click 'Find'
4) Now double click it and change the hexadecimal value to 400 which corresponds to 1024
5) Click 'Find Next' and repeat Step 4)
6) Now do the same for ' DefaultSettings.YResolution ' (without quotes) and change the hexadecimal value to 300 which corresponds to 768 and restart.
If you want a setting other than 1024x768, I have no idea what the values for those would be.