As a point of interest I discovered almost all of the internal screws loose on my 500mhz tibook after about 2.5 years of use, both under the keyboard and after removing the bottom. I was trouble shooting an intermittent shutdown. This PB had not been anywhere for servicing--other than me replacing the HD, DVD optical disk and Memory--none involving those loose screws. I do travel a lot and the machine has gone between home and work every day. (My trouble shooting did not work and applecare replaced the battery wiring harness.) Jesse Proudman wrote: > I solved my overheating issue. It had nothing to do with overheating at > all. Apparently, the last time I returned my laptop to apple for > service, they never tightened down all the screws under the keyboard all > the way. What was happening was keys on the keyboard were then hitting > this screw and some how put the computer to sleep. I tightened the > screw and the problem went away. > > Thanks for all those who answered. >