Arggghh. All of a sudden my 2 month old Mac Pro is putting itself to sleep randomly and constantly. Well I say sleep but the screen is black and the power light is not flashing like it normally. It's not software or system or the hard drive as I have tried swapping the drive and with an emergency clone I have. It seems to be hardware. I've tried restarting and sometimes it won't restart. I've tried resetting the PMU and the VRAM, zapping the PRAM. Nothing. If I hit the volume up button there is no volume up or down noise so it's like its dead. Bu if I hold the power button down and shut it down it will restart only to last 5 minutes to 20 minutes before it does it again. It really is if it's just sleeping but it won't wake. Any ideas? I've tried everything. Have a big job on at the moment, it's really BAD.