As an FYI for any keeping tabs.
I have similar problems on machines that should otherwise fit the specs listed, ie: OS 10.4 and 32 bit colour. I assume it is the graphics chipsets. The rage mobility in a Pismo, and Rage 128 Pro in an AGP G4. I do not have an issue on a 15" iMac G4 with the GeForce2 MX chipset.