I've got an old Macbook Core 2 duo, 2 GHZ, running 10.5.8, 2GB RAM. It won't stay on for long and shuts down,especially if it's moved. And then it reboots on its own, only to repeat the process over and over. Haven't been able to use it much. Sometimes. I'll boot it just to see if it stays on..and it may for 10 seconds or 30 minutes and then it reboots on its own. Or it will be off and seemingly reboot all by itself. I'm beginning to think it's possessed. I've tested the RAM, wiped the drive and installed a new 10.5.8 system by docking it to another computer. It doesn't need the firmware update. The only time it will not "act out" is when I'm zapping the PRAM. I can do that til the cows come home. Tried a different drive. No luck. Doesn't matter if power cord is on or off. Battery appears to be good in Sys Profile. Sometimes when it shuts off, the fan or drive continues to run and battery drains if no ac. otherwise,battery charges fine. I've tried resetting the SMC. Opened it and didn't see anything loose, I've even disabled the SMS (sudden motion sensor) through the terminal. Sometimes it stays on if left alone and not moved. But the phantom rebooting is very weird. It will also shut itself off at any time, even if it's sitting on its own and not moved, and then reboot. I'm guessing something loose, but I didn't see anything obvious. Has anyone experienced this cluster of symptoms or have any ideas? Thanks!