I have a Macbok pro Intel core i7 Boot rom version MBP81.0047.B27 and a windows 7 64 bit. I have been dual booting for a couple years now,but it has been mostly in Win 7. The last couple weeks I started to work on Mac OS X, but when I turn on my laptop it goes straight to Mac OS X and gets stuck on the loading screen. I waited for literally 30 mins to 1 hour and it wouldn't do anything but stay on the part. I tried to reboot several times and it would just get stuck on that part. The part I am talking about is where you see the icon of MAC with a bar at the bottom. Similar to the image I attached. There are times where it does successfully boot up into the OS, but that's after several attempts. I've been loooking online for anything, but haven't found a solution yet. Does anyone know what is happening and how I can fix it? Thank you.