After no problems this afternoon (or for the last two years), I turn on my macbook with OS 10.5 Leopard (no recently installed new software) and all I get is a grey screen. No spinning wheel, no ? mark, no message. Just blank. Tried rebooting with install disc, to no effect. Tried burning a firmware restoration disc on my other computer (thank goodness for it!), and no effect on macbook. Can't get it to boot into single-user mode either. Either there is some technique I am missing, or perhaps I have just encountered a grey screen of death? Help? Anyone?