FF and TB running on wrong computer

[D. R. Evans]

This is very strange...

computer A is running dapper; computer B is a laptop running an old
Mandrake distribution.

Sitting at the terminal for computer A, I ssh into computer B.

The login goes fine, although there is a not-very-comprehensible message
about forwarding:

----

[H:~] ssh laptop
n7dr at laptop's password:
Warning: No xauth data; using fake authentication data for X11 forwarding.
Last login: Thu Sep 13 07:06:00 2007 from 192.168.0.190
[L:n7dr]

----

On the ssh command line for computer B I now start FF (or TB). The
resulting session of FF or TB runs on computer *A*. How on Earth can that
happen? And given that it is happening, how do I stop it?

I sort-of assume that it has something to do with that message during login
time, but it's still a bit of a mystery how a command to run a program on
computer B causes it actually to run on computer A -- I can tell that it's
the FF from computer A because all the bookmarks and history are those for
computer A; in fact, the two computers don't even have the same version of
FF, and it's definitely the computer A version that's started, even though
I'm typing it on the command line for computer B.

Really, really weird.

The only programs that seem to do this are FF and TB. All other programs
behave exactly as one would expect (i.e., the computer B version is
started, but the window appears on the screen for computer A).

  Doc