I've had this problem with the 2.6.32 kernel ever since I compiled it at rc5. If I use my computer for an extended time, the computer's I/O begins to hang. If I shut down my laptop and start it again, the power LED and fan wake up for an instant, and then it shuts back down. It then tries to start itself again, but the same thing happens. This will go on and on until I intervene with a hard shut down. I can "fix" this problem by pulling out the battery and holding down the power button to release static. I'm not sure why this works, but it does. It only delays the problem, as after I do this and start using the laptop again, it will eventually happen again.
This has happened with Debian's 2.6.32 kernel, as well as Arch's 2.6.32 and up kernels. The only distribution I've used that this doesn't happen with is Fedora. Any advice?