Hi all, A friend has asked me to help with his computer - he has a Macbook Pro, and the issue is that OSX isn't booting, while his Windows 7 is. We get the boot screen, allowing us to select either Windows or "HDD", the latter pertaining to the OSX installation. Upon clicking it, the loading screen comes up, with the spinning grey circle...but it doesn't boot. I've tried booting in safe mode, and in this instance I can get the booting bar...but it fills to only about 70% before disappearing, leaving me with the same problem as before. He hasn't used the OSX installation, so we're not opposed to obliterating it at all....my thoughts were to just reinstall OSX, or simply...install OSX on that partition - if that's quite straightforward? Essentially, I want to do this without messing up the Windows installation, which while we have backed it up, we don't have the disc for.