I have searched many black screen posts, but the symptoms seem to be related to various problems. Please help mine. I changed the hard drive on my 2008 Macbook Pro from 160 to the Seagate 500gb 7200 drive. It booted fine into the install disc. Transferred all my data from the Time Machine backup, then loaded snow leapord and all updates. I used the computer for the rest of Sunday and Monday evening. End of Monday evening I was watching Hulu Desktop. I left Hulu full screen, and shut the lid for the computer to go to sleep. Next day, open the computer, black screen, no boot, chime on first boot after battery is replaced intermittent on each startup after, and solid white led on front. I can hear fan and a disc spinning when I put one in. But when it is a start up disc, it does not boot from disc, or at least that I can see from the screen as it is black. I read that it might be heat...so I left it battery disconnected for a few hours. Nothing. I swapped memory modules to different configurations, and nothing. I also tried resetting PRAM, and still nothing. Please help diagnose...I don't want to take this in for apple care now that I changed the hard drive. Thanks!