Funny, it works sometimes but not others? I have changed the filenames of all media to something nice and short with no special characters or spaces. Any other ideas please?
Another idea: check the Xine_Player logs (the DCE device that actually plays the video). The best would be to do two steps:
1) add/modify line in /etc/pluto.conf to contain "10" in LogLevels value. e.g. LogLevels=1,2,3,4,5,6,7,8,9,10 then do a quick router reload
2) try to play the file and then post here the contents of logfile: /var/log/pluto/22_Xine_Player.log (note, if your Xine has different device ID, you will have something else instead of 22).
This way we can look in the logs and see what the issue is.