For quite a while I've had a Samsung 1920x1200 23" monitor - which on boot would show the user icons at the correct resolution, then switch to 1920x1080. Ecah time I would have to manually chnage resolution to the correct 1920x1200 which then worked fine.
I thought this was a quirk of the AMD/Samsung combination until yesterday when my new Dell Utrasharp 27" monitor did exactly the same, booted at 2560x1440, then reverted to 1920x1080. Again I can switch it to the correct resolution - but this is getting boring.
What obvious solution am I missing? :-)