ssh, window managers, and xorg

[Xian]

I use xorg and it works well for everything local. To test it I started xorg 
with just xterm as the client like so:

% startx /usr/X11R6/bin/xterm

In this terminal I can start a window manger such as twm and it works fine, 
but I can't start a window manger on a remote machine:

% ssh -Xf some.machine twm
twm:  another window manager is already running on screen 0?
twm:  unable to find any unmanaged screens

I can use ssh like that to start an xterm or any other xclient on another 
machine tho. I don't think the KDE window manger has much success either cos 
when that is started remotely none of the windows have borders but it doesn't 
complain.

I can do exactly the same things on a machine using XFree86 instead and they 
all work fine. Do i have to tell xorg to allow remote window managers or 
something? or dose it have a window manger built in that I have to disable?

I have found this to happen on my workstation and on the FreeSBIE CD that I am 
trying to use at college. 

Any help will be very much appreciated. Thanks in advance.

-- 
/Xian

"In C we had to code our own bugs. In C++ we can inherit them"
unknown author