Ok, I have a 2007 MBP. Issue started because it froze up (some lines show up on the mouse pointer and then it freezes in place) and then after hard restart, it wouldn't go pass the grey screen. I reloaded the OS. It worked for about 20 minutes then same thing freeze and fan stayed running. Took it to the apple store and they said the hard drive is probably going out. Fast forward to now, installed a new seagate SSHD. And while loading new OS (snow leopard) I got as far as the portion where it asks for you to take yoir picture and it froze again. It said, a disc was ejected incorrectly and then it froze up with the fan running. Same as before. Any help, would be greatly appreciated as I am frustrated beyond belief.