can't cleanly log out of ssh

[rajiv at alum.mit.edu (Rajiv Aaron Manglani)]

> Ok, so after having left an ssh -X session open for a few hours, I  
> now get the following when trying to run xclock:
> Xlib: connection to "localhost:10.0" refused by server
> Xlib: Invalid MIT-MAGIC-COOKIE-1 key
> Error: Can't open display: localhost:10.0

i used to have this problem. switching to 'ssh -Y host' solved it for  
me (though i am not exactly sure why, and i only use it between my  
own trusted hosts). note from the man page:

      -Y      Enables trusted X11 forwarding.  Trusted X11  
forwardings are not subjected to the X11 SECU-
              RITY extension controls.