XML-RPC Datamapper problem

[eluser]Unknown[/eluser]
[quote author="tomcode" date="1250258545"]Don't know neither XML-RPC nor Datamapper, but it looks to me like Your User library might have some whitespace outside the PHP tags.[/quote]

Yes!!! Thanks tomcode, that was the issue. My 'user' model class had trailing white-space on the same line as the closing php tag.

Code:

<?php
class User extends DataMapper {

    public function __construct()
    {
        parent::__construct();
    }
}
?>   // the problem was the white-spaces here

Thanks again for your help tomcode.
Cheers,
Matt