hello, my ibook is having a serious problem and need some advice/help. the problem is that when i start it up, i hear the chime but no gray screen with apple logo comes up. i can hear the hard drive and am pretty sure its booting but after a little while the blue screen comes up and i can get to the desktop. i can then use the computer for about 1 min. but then all of a sudden the computer will go to sleep. i can wake it but the screen wont come back but i can faintly see the desktop so i thought the backlight went out. the thing is when i boot off the cd the screen will hold all the way thru a reinstall but once its finsihed and reboots, once again no gray screen but i hear the chime and then goes to sleep again. also the keyboard doesnt work when im asked my name,email,etc. during the registration proces. it wont go to sleep throughout the whole install routine so im having a hard time trying to pin point whats wrong with the computer. i have tried the pram (4 chimes) and reseting the nvram but no go. also tried reseting the pmu but im not sure im doing the pmu right. ive read that im suppose to simultaneously press and then releasing Shift-Control-Option-Power on the keyboard and have done that but when i do, since the screen is out, it sits there for awhile with me holding down the keys and then it boot into safe mode so not really sure if im succesfull at resdeting the pmu. took it to the apple store and they say its a logicboard swap but im having a hard tie beliving it because it works fine when i boot off the cd. its the same with either the battery in or out. can anybody help me out or give me some advice? thanks!!!