Help. Just put a new HDD (Seagate Momentus 750gb) into my Nov' 2010 15'' MBP. Everything backed up with TM before switching the discs. Drive swapped out no problem. Turn on MBP and insert Snow Leopard disc expecting it to boot far enough for me to get into Disk Utility so I can format and restore. MBP turns on, goes to folder/question mark, which turns into Apple logo upon insertion of the SL disc. But that is as far as it gets, just hangs on the Apple logo screen indefinitely. Have I done something wrong? How do I get past this screen?