I haven't tried using 2.3.99pre5 yet. Is that the one you're having trouble with? I had no problems at all using the pre2 usb drivers on a single processor machine (this was using the non-alternate uhci driver).

Actually you might know this, John. Do you have any idea why the alternate uhci driver is much slower than the non-alternate one? On my machine it's almost an order of magnitude slower.

Richard