I'm having issues with my MBP booting up, it gets to the screen with the hourglass then goes grey and says I need to reboot. When I reboot it it does the same thing. I have taken it to the shop 2 times in the past week and they have gotten it to work, but when I get it home it starts doing the same thing after a couple hours (maybe 30 minutes actual use). They have reloaded osx 10.4 each time telling me that they tried to load 10.6 and 10.5 (i think) and it didn't work. does anyone have any ideas? I am ready to throw this thing through the window