NetworkManager in Intrepid breaks my FreeRunner's Internet connection

[Jeffrey Ratcliffe]

I've just upgraded my Hardy desktop to Intrepid and now have network problems.

This is my /etc/network/interfaces

auto lo
iface lo inet loopback

auto usb0
iface usb0 inet static
       address 192.168.0.200
       netmask 255.255.255.0
       network 192.168.0.0
       up iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 &
       up echo 1 > /proc/sys/net/ipv4/ip_forward &
       up iptables -P FORWARD ACCEPT &
       down iptables -D POSTROUTING -t nat -j MASQUERADE -s 192.168.0.0/24 &

This worked fine with Hardy, but the desktop cannot see the network.

If I comment out auto usb0 and everything below, I can access the rest
of the network, but then, of course, my FreeRunner no longer has
Internet access.

Any ideas on how to get both up?

Regards

Jeff