I have got RealVNC Server running on a Windows machine and have no problem connecting to this using RealVNC Viewer on another Windows machine (suggesting there are no firewall problems).

Tried installing and using VInagre on Ubuntu 12.04 Desktop. Ran the Remote Desktop Viewer - it found the Windows machine as an available host, but on attempting to connect, got the message "An Error Occurred" then "Connection to <address> has been closed".

Any ideas what is going on?