Hi all. Once last week and once yesterday, my Ti 15" Powerbook would not start up after being in sleep mode. What I usually do is press the power button and I can hear the machine turning on but the "tune" is not played. Then I hold the power button for about 3-5 second and I hear the machine turn off. But nothing is displayed on the screen and the processor is not crunching. Eventually after much manipulation, the system turns back on normally. I want to add that the battery is full charged and I've tried different power supplies. I got it working obviously last week, but this same situation happened yesterday afternoon. So I made my first call to Applecare, which the fellow was very helpful, and he is sending out an empty box. The only thing he had me do over the phone is lift the keyboard and press the reset button, and then do a button combination of option + apple + power? and something else. I'm sure you guys know what I'm talking about. Well to no avail, the machine didn't turn on. But like the first time, I played around with the machine's power button here and there, and finally it turned on and I am typing on it as we speak. So my question is, do any of you have any iota on what's going on and should I still send it in to Applecare? I don't want to send it in and have them send it back to me saying nothing is wrong. My feeling is that it may be the screen or motherboard? But I'm not sure Any help is appreciated - thanks!