So I got the folder with ? mark upon reboot. Stats bout my mac... 10.6.?? ; 2.26 GHz ; 4gigs RAM ; Seagate Olympus 500gb HD, 5400rpm - Windows 7 bootcamp on separate partition ; purchased Dec 25, 2009. Just recently replaced battery back in January '11. I was using google chrome, closed my laptop to watch a movie, then opened it back up and it (Chrome) froze up a couple times. I forced quit it, opened it back up, froze again...however this time the entire computer froze up. Forced Restart by holding in power button, then got the notorious Folder with flashing ? Mark. I have read that the problem can either be a Logic Board, or a Dead Hard Drive...but keep reading, this hard drive works fine externally. I tried all the steps, holding down ALT Key ; shift key ; c key ; booting with the install cd and running disk utility to search for the boot drive...NONE of which worked. I removed my 500gb Hard drive (purchased in January) from inside my Mac, replaced with original 160 gb drive and swapped the 500 into the external enclosure. Mac Booted fine with 160. Heres the kicker...the 500gig showed up when it was attached to computer. I restarted, and even booted MacOSX from the External (500) with no problems. It seems the problem is when the 500 is trying to boot from inside the MBP. I cloned (using SUPER DUPER) the 500 to another external HD (ie: External to External). Booted fine from the new clone. I am currently using WINCLONE ISO of the bootcamp...and attempt to Wipe, reformat, and then RE-Clone to the 500 to see if that does anything. If anyone has any suggestions I am up for anything. I feel im going the right way about this (cloning 500, then reformatting and cloning back to it)...but who knows. Thanks advance everyone! ----------------------EDIT----------------------- Re-Cloning from the other external to the 500 HD did not work either? Im considering a fresh install of MacOSX while 500 is connected externally, replacing it internally and seeing if hopefully it will boot then. Any Tips please? Next week is finals week and I really need my laptop.