Hello, I'm running 10.4.2 on a PowerMac G4 Dual 1 GHz (MDD), and I've had this problem since I installed 10.4. After running for a while (perhaps 30 minutes or longer), using Exposé to reveal my desktop (by pressing F11) will only hold for a few seconds. The time that the desktop remains showing varies from immediately closing back to 5 seconds. I can't find any particular program or function that this happens after; it seems to be random. (Nothing is happening that would cause it to close back either, such as launching a program.) Does anyone know what could be causing this [mis]behavior? Thanks a bunch!