screen resolution jumps when I dock and shut screen

[scott11]

R61 7734
I have it set so when I dock the notebook lcd turns off and the external is the only screen. When the notebook is open (screen off) the resolution is 1280x1024, that's what i want. When i close the notebook the resolution jumps down to 1024x768. How can i close the notebook and keep 1280x1024?