Okay, After a LOT of trial and error testing, I've determined that my iPhone is crashing the highspeed driver for USB on my computer (AppleUSBEHCI) - but it doers NOT crash the low speed driver.

iPhone : vers 1.1.1. Dual 2.0 Ghz G5, running 10.4.10

I don't know if this is an iPhone problem or a G5 problem.

The issue happens when:

1) The iPhone is plugged into a USB 2.0 port on the G5, or into a USB 2.0 powered hub. It will appear to connect for sync and charge normally.

2) Then, any handshake or other communication with ATT over the cell network (determined as I have an audio device very close to the iPhone, and can hear the "handshake nosies") will result in the "High Speed USB Bus" to crash - not only for the iPhone, but for any usb 2.0 device connected to any USB 2.0 port on the G5.

USB 1.1 devices are NOT affected - in fact, I can plug the iPhone into a USB 1.1. hub, and can sync/charge over USB 1.1, even though the USB 2.0 "bus" is crashed. Only a restart can bring back the USB 2.0 bus.

Sometimes I get a "low power USB warning" (in fact, two at once).
A theory is that the iPhone is drawing too much power during communication with the cell network, then disconnecting from USB in an ungraceful way, causing the crash.

Does anyone have any thoughts? Suggestions?

I have:

Restored the iPhone

Reinstalled Combo Update 10.4.10

Deleted and reinstalled iTunes and related mobile device extensions

Thanks for any input.