I installed Linux Mint (although I think I used to have the same problem on the latest Ubuntu 11.04 too) and I only have one problem. I plug an HDMI cable into my laptop to put the display on my high-res monitor and set the display up (switching off the laptop's own display), but after a variable length of time it resets to 'same display on both monitors', switching on my laptop display and screwing up the resolution on my external monitor.
This gets pretty tiresome after a while. Any ideas what the problem might be?