help with usb network

[glenn <gdavy@tpg.com.au>]

I'd like to attach my zaurus to my debian box from its usb cradle. The
problem I'm having is that when I plug the Z in, or modprobe usbnet, the
machine grinds to virtual halt for aprox 2 minutes while it registers,
unregisters and reregisters the device - at least thats how I
interperret it - this is a snippet from syslog: 
----
kernel: usb 3-1: new full speed USB device using address 88
kernel: usb0: register usbnet at usb-0000:00:1d.1-1, Sharp Zaurus
SL-5x00
kernel: hub 3-0:1.0: port 1 disabled by hub (EMI?), re-enabling...<6>usb
3-1: USB disconnect, address 88
kernel: usb0: unregister usbnet usb-0000:00:1d.1-1, Sharp Zaurus SL-5x00
kernel: usb 3-1: new full speed USB device using address 89
kernel: usb0: register usbnet at usb-0000:00:1d.1-1, Sharp Zaurus
SL-5x00
kernel: hub 3-0:1.0: port 1 disabled by hub (EMI?), re-enabling...<6>usb
3-1: USB disconnect, address 89
kernel: usb0: unregister usbnet usb-0000:00:1d.1-1, Sharp Zaurus SL-5x00
------
Eventually these errors creep in to syslog:
----
kernel: usb 3-1: unable to read config index 0 descriptor/all
kernel: usb 3-1: can't set config #1, error -75
----
If I ifconfig I have no usb0, so  I ifup usb0 then I get:
----
thor:/etc/network# ifup usb0
SIOCSIFADDR: No such device
usb0: ERROR while getting interface flags: No such device
SIOCSIFNETMASK: No such device
SIOCSIFDSTADDR: No such device
usb0: ERROR while getting interface flags: No such device
SIOCSIFMTU: No such device
usb0: ERROR while getting interface flags: No such device
Failed to bring up usb0.
----
In /etc/default/hotplug I have NET_AGENT_POLICY=all

The config for usb0 in /etc/network/interfaces is:
----
#Zaurus card
iface usb0 inet static
address 192.168.129.1
pointopoint 192.168.129.201
netmask 255.255.255.255
mtu 1000

mapping hotplug
        script echo
----

What am I missing here?
Thanks
Glenn