Hmmm... I have this problem with my G4/400 and USB devices. (I'm past my warranty :-\).
It started a few months ago... Any USB device I plug in seems to crap out for a second or two, and then come back into action, no matter what the device is. Unfortunately, in a game, it's usually timely in crapping out, but not coming back

.
I had to boot into Firmware for something, and it gave me about 100 USB Setup Errors (I thought that was odd

).
Anyone have any idea what's going on, and what I can do to fix it?