Download multiple files by clicking a single button - fixed and example posted
[Updated 6th July 2011 - issue fixed, example attached for others that may need to know how to do this]
I fixed this with some hand-written php code and framework builder I've attached it to this post for anyone wanting an example of how to do this.
The attached file was added as a plug-in to a page with a form on it and the trigger was set to run the plug-in when the button was clicked.
Works perfectly and provides a link to download the files to the local PC drive.