I have a 1.67 15" powerbook g4. For some reasons I haven't used it for about 2 months, just put it in the laptop bag and left it in the closet. The last time I used it was functioning well, except the starting up is a bit slower. Today I just opened it and it couldn't start up at all. When I press the power button, there was the normal sound came up and about 20 seconds later the gray screen appear with the apple logo, there was no spinning wheel under it as usual and just like that no mater how long i left it there. I tried many things i could found from webs like resetting PMU (http://support.apple.com/kb/HT1431), go to safe mode, target mode... but all useless. Can you help to tell me what to do? What cause my notebook this problem and how to solve. I think I have to take it to the technician because i don't have the boot CD, but all my data is in this machine and I really don't want to lose them. I'm desperately needing help! Thanks for your response ASAP!