2.6.21-rc6 USB Keyboard hangs (EHCI/UHCI/HID)

Please Cc: me on replies, as I read linux-kernel sporadically and am not
subscribed to linux-usb-devel at all.

Greetings,

I have seen my USB keyboard drivers lock up several times now with my M$
Natural Ergonomic Keyboard, both on SUSE 10.2's current kernel as well
as 2.6.21-rc6 today. I don't ever recall this happen with older SUSE
10.0 kernels. The keyboard is connected to a USB2.0 hub with single
transaction translator (at least that's what FreeBSD 6.2 says), which is
connected to a via root hub.

Symptoms are that the keyboard LEDs go off and no further input is
impossible (I'm typing this into a PS/2 keyboard). Replugging does not
help. Trying to unload ehci-hcd hangs modprobe, and additionally I've
got a stuck khubd (not sure if that's related), else no logging.

I'm rebuilding the kernel with HID/USB debugging cranked up to see if I
can get some detail out of the situation. Any specific kernel debugging
options that might help me debug this further?

Thanks,

-- 
Matthias Andree