I have a new Mid-2009 13" MBP and I had just recently upgraded to SL. Well, last thursday my Mac would not boot up. It turned on, and got as far as the screen with the apple and spinning gear below it. However, instead of continuing on to the log in screen, the gear just kept spinning and it never advanced anywhere. So I got a hold of tech. support and they walked me through the standard trouble shooting (i.e. resetting the various RAMs and such) and repairing the disc, trying to just install over the current installation.... all failed and did help any. So, I erased the entire drive (was able to save everything though using target disk mode and firewire, which I had to order and wait for it to come by mail order because no one has any firewire 9pin-9pin in stock....), and tried to just install SL... and it failed. So I erased it again with the original Leopard install disc, and did an install on the drive and it worked and now I'm typing you from my computer. So what is up with that? SL just not like my machine or what?