The XML page cannot be displayed when embedded

I embedded gallery in to my website using a tutorial from the forum. I created the gallery2embedded.php file. Very simple and straight forward. However, the only problem I'm having is when I click an album, start looking at pics, then click the link on the upper left to bring me back to the main album page in gallery, I get this strange The XML page cannot be displayed error (see full thing below). I've done tons of searching on Google and can't seem to find a solution. If I hit the back button, no problems at all. Could anyone take a guess on what might be wrong? Thanks! Brad
Here's the error.

The XML page cannot be displayed
Cannot view XML input using XSL style sheet. Please correct the error and then click the Refresh button, or try again later.

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Only one top level element is allowed in an XML document. Error processing resource 'http://www(domainname)

<b>Warning</b>: Cannot modify header information - headers already sent by (output started at /home/martini/pub...