Ok, we have 3 NW6.5 servers in our tree, each of which is at separate
location, linked by a WAN. We've noticed that when the WAN is down, users
are unable to login using contextless login; there are no errors but
windows asks if we want to login locally. The default server in the
client is set to the local server.

I've been able to replicate this by setting a static IP and omitting the
default gateway.

Any ideas?