I've run into a terribly annoying limitation with my 4870. I just hit my HDMI switch to pop my main monitor over to my PS3, and CCC nuked my multi-monitor settings. It chucked the taskbar and all my windows over to the 2nd monitor, then when I switched back it just readded the main display as a clone of the 2nd one, forcing me to reload my CCC profile and wait for about 15-20 seconds while the screens flashed and it reconfigured everything back to how it's supposed to be. Can anyone think of a way around this? 

