i will try and reconnect the smaller display just for the screenshots, need to get it out of starage. i was quite happy with the new 1920x1200 one.
I had to come back for this, i can now reproduce it:
When the 600GS starts up while the Monitor is not ready/plugged in, the behaviour occurs, it starts up in low resolution and the settings are greyed out.
also, while the low resolution is in use, there is no way to access the lower left options anymore as the move out of view instantly.