Keyboard & Trackpad freeze

I am running leopard on my macbook and occasionally, after several minutes of my macbook idling without going to sleep, the trackpad & keyboard become unresponsive. The only button to work is the power button. An external USB mouse will work. A restart will remedy the problem...until the next episode. Anyone have any ideas?

I have the same problem! I too am running Leopard, but on a Macbook Pro. Can someone please figure out what's going on? Im about to perform a complete OS reformat, and just reinstall Leopard.

did you manage to solve the problem? i reformat and reinstalled but it has since happened once.