Thanks for all the testing isophia, I have an almost identical setup, I have MP 1,1 and a 8800GT currently, and have to drive a dell 24", and a dell 27".. the 27" has a Display port, but not MDP, and i've heard about issues on dells site concerning its DP
Silly questions but have you tried, having both the 8800 and the 5770 in there, and using a DVI from each?
Have you tried both MDP's.. or silly as it sounds making sure the MDP cable is in all the way to the card ( i read about ppl not realizing the connector goes in further)..
Have you tried, reconnecting the MDP cable? I believe that is what has worked for ppl that had issues with the monitors not coming back on after sleeping.
With all the issues, ppl are having MP 2010's included.. hopefully 10.6.5 solves things.. or ATI figures it out.