I took my MB in for repair a week ago because it kept shutting itself off randomly. They replaced the logic board and gave it back to me. It was working pretty good, didn't need to use it much so I never really turned it on more than once to see if it worked. Now everytime i start it up, the "ta-da" sound goes, but the screen stays a very dark gray and nothing happens. The machine is running but nothing shows up. So i reset the PRAM and it works. Problem is, almost everytime i turn the computer off, I have to do this. Faulty logic board.....again?! It's a shame if it is because it is running so nice now, cooler, no moo, no whine... nothing!!!