My trackpad stops working if the computer screen goes to sleep for a while. I'm not sure exactly how long it takes but i know that when i leave my computer for about a half hour or so and come back, the screen is asleep but the computer is not (which is normal according to my settings) but when i touch the trackpad, the cursor hardly moves. It's very skippy (almost like when running the hardware test, which i was told was because the firmware for the trackpad isn't running or something..) but then i put my palm on the trackpad to reset it and the trackpad starts working again. And it happens every single time. But it has to be for an extended period of time. If the screen just recently went black and i use the trackpad then it's fine.
I have a 15" 1.67 ghz powerpc powerbook. It's the 2nd to last powerpc model (before they added a dual layer burner, bettery battery life, hi res....
I've had the computer for almost a year now and have never had a problem with the trackpad..