I believe you talking about the onscreen geometry? When you first turn it on or wake it from low power state the desktop appears to have expanded beyond the edges. So you adjust your geometry controls... probably more then once tho...
Although this may not be the case for your monitor. This is especially true with the larger ones. I have a 19" Trinitron that does the very same. after it warms up the display shrinks to its normal state, it takes a couple of minutes. So try leaving alone your controls next time and just give it a few minutes. Let me know if I understand you correctly.

§tatic, that makes sense. it always seems to be after i've had my monitor turned off all night while i download. the screen is huge in the morning. i'll try to wait a few minutes to see if it warms up to its original state.

Voodoo_FreaK, i'm running the 31.40 detonators.

My monitor started making a pitched noise when i was running it at 85hz. I ran it at that rate because it was recommended by the owners manual. The tech guy on the phone I should change it to 75hz and that it's best to use 10 less than recommended. Now my monitor doesn't make noise and there isn't much difference between 85hz and 75hz once you get use to looking at 75hz.