Thanks very much, Thomas. You're right that it's not
a very helpful error message. However, I *think* that
the problem, as you pointed towards, is in one of
the post-install scripts; the one for XML-SAX missed
some proxy settings that were required to work within
a proxy environment. I, hopefully, fixed this - please
let me know if you encounter similar problems in the
future.

Also, please let me know how you get on with PAR-WebStart;
I'm curious to see how it works for others. Thanks.
And sorry it was such a pain to install, but as you say, your
experiences will help others :)