tramp hangs

[gebser]

Reading along another email on this list, I figured I'd give tramp a try
to a local box.  I did "C-x 4 C-f ..." and the minibuffer announced
activity like unsetting variables.  Then it showed "tramp: setting shell
prompt" and hung there.  And it's been hanging for about ten minutes.  
I have three emacs frames open and all three are hung.  (I can't run any
commands, can't even move the point, not with the keyboard and not even
with the mouse.  Can't open any menus either. 

I'm using emacs 20.7.41.


Any help appreciated.