I'm having the same problem that others are describing here and have been unable to resurrect it since it stopped working. I enabled eyefinity maybe a half dozen times since I got it. What a disappointment.
I'm rocking this exact arrangement
http://www.ubergizmo.com/15/archives/2006/02/dell_3007wfp_on_dell_2001fp_action_8_megapixel_desktop.html. Which isn't supported so I have to run them all at 1600x1200 in landscape mode. Another disappointment--however not nearly as bad as it not working.
My impression of the CCC, since it's initial release, has always been a clunky application. But this bug is particularly egregious in my opinion.
Not to mention I dropped around $600 for the 5870, the active DP->DVI adapter, and cabling. (Not including the monitors).
Just for completeness on my particular setup: HD5870, 2001 Dell 20.1" 1600x1200 via HDMI v1.3 cable into the 5870 HDMI port, 3007 Dell 30" 2560x1600 via Dual DVI into the 5870 DVI port, and a second 2001 Dell 20.1" 1600x1200 via HDMI v1.3 cable into the Dell Active DP->HDMI then into the 5870 DisplayPort (active converter powered by motherboard USB directly). (ati driver v9.12)