If you setup X11 forwarding in putty. Then after SSH to server and user change via su then error could ocurr.
Xlib: connection to “localhost:10.0″ refused by server
Xlib: PuTTY X11 proxy: wrong authentication protocol attempted xterm Xt error: Can’t open display: localhost:10.0
To solve, back to oryginal user:
issue:
>xauth list
localhost:10 MIT-MAGIC-COOKIE-1 b31fa494b952390070d409890a314cfb
then on new user:
> xauth add server/unix:10 MIT-MAGIC-COOKIE-1 b31fa494b952390070d409890a314cfb
