Connection failure [1]

I have been using xmanager without any problem. Today all of a sudden i am getting this message and I can not connect to the server(dc.umd.edu)

X11 channel request arrived.
Establishing X11 connection (id=1)...Done.
Xlib: connection to "localhost:18.0" refused by server
Xlib: Xssh: Invalid x11 authentication cookie!
Error: Can't open display: localhost:18.0

Waiting for forwarded connections to terminate...
The following connections are open:
#1 X11 connection from 127.0.0.1 port 4222 (t4 r1 i2/0 o0/0 fd 17/17)

Thanks
Ali

Check the permission of "$HOME/.Xauthority" file. It should have a write permission to save X11 authentication cookies.