My powerbook is acting strangely. When I boot the PB it chimes as usual and I can hear the machine coming to life. The screen goes from black to grey, too. However I get no apple logo, no spinning status circle thingy and no characters. The machine appears to function normally, yet, I get no visual of anything except a grey screen which can be dimmed and brightened. can someone Please tell me what is happening? Is my display dead?