xhtml:script and IE, integrating BIRT reports

I'm having an odd problem I haven't seen before, but only with IE (though maybe it's because I haven't been using IE much recently?).  My page contains JavaScript function calls.  In the xhtml:head section, there is an xhtml:script tag referencing the javascript file where these are declared.  However, in IE, when the page loads I get an error about object does not exist for each function call in the page.  The JavaScript file *is* loaded however, because it attaches some code to the body's onload.  It's just the file gets loaded after the JavaScript calls in the bdoy are evaluated.  I tried to put defer="defer" in the script tags within the page body, but this only works for script tags where src is used, not for inline code.  What could be causing the JavaScript to load late?

I have Orbeon configured as a filter in my app using the separate deployment documentation.

Perhaps I should post to the BIRT project forums as the reason I am doing this Javascript is because their JSP tags don't produce valid XHTML... :)  But I'd like to see if there is some other solution first.