I have a Pismo G3/400 that has suddenly developed a really wicked overheating problem. Basically, I can only use the machine for a short while before it freezes completely and will not turn off or on again. Letting it cool down for increasingly longer periods of time allows me to use it for a longer amount of time before freezing. This is a problem that just developed today. Both the round part of the power adaptor and the bottom of the Pbook get quite warm, although it's hard to say if they get any warmer than usual. I tried resetting the PMU with no success. The fan doesn't seem to function, although I don't remember if it ever did. Any ideas?