Why is adding a new Ubuntu PC to an existing LAN such a pain?

Sat Jan 20 20:54:38 UTC 2007

I've done this several times now and the result is always the same.
Running a mixed LAN of Windows XP and Ubuntu 6.10 machines always causes
the latest Ubuntu addition to just freeze after the initial install and
reboot. Any attempt to bring up a terminal, configure the proxy, insert
a network address or just about anything just results in the mouse
pointer going 'busy' for about ten seconds and then nothing happens.
Most annoying.

The first Ubuntu machine is configured easily but add any additions
after that and something gets very screwed.

        Bob