Java SE (Java Platform, Standard Edition)

I keep on getting the above error when trying to webstart a very simple application (1 class). Originally trying to get this to work with a much more complicated application and decided to try a hello world app to get the thing up and running :-)

class is jarred up in 'classes.jar'
the format of the JNLP file 'appears' to be correct, but the resultant error is ..
unable to load resource http://dl_antiochus.eu.fore.com/classes.jar
this despite the fact that classes.jar is definately in the doc root of the server (apache) and sticking the above URL into the address of the browser doesnt throw any exceptions (get jar binary loaded into the browser with no problems)

Proxy is setup correctly, MIME types are setup correctly, webstart is installed on the client machine and this is slowly driving me nuts !

anybody got any ideas