I always keep my mac pro on the table as i know they are great hoovers for dust. Recently i was alarmed to find both my 30" screens going blank for no apparent reason. Trawling forums and apple discussions i found a lot of similar cases but with different solutions. Of course i panicked and feared the worse, could it be a new logic board was needed or a new graphics card the horror ! However after a deep breath i logically started with the least possible problem. I opened the computer and carefully cleaned out all the dust particularly on the graphics card, hey presto back to normal !! I hope someone in my predicament finds this thread one day and it helps them. I used a dyson hoover to clean although i read this can produce static i took the risk as i don't have access to an airline or a can of compressed air. Dust creates heat which in turn shortens hardware life, everyone be carefull and keep your mac clean, i would also encourage people to keep it off the floor.