My 2007 iMac won't boot past the grey screen, not even with the Apple logo in the centre of the screen. I've tried booting into the Boot Manager, tried using the recovery partition, tried booting from an external USB and FireWire drive, reset the NVRAM, reset the SMC, tried booting with a DIskWarrior boot disk (can't even eject the disk now... i've tried holding onto the mouse to force eject), changed the RAM back to the original... Anyone else have any suggestions? I can't really figure it out and i need this machine up and running. I appreciate the help!