Ok, I'm still getting used to what is acceptable in PHP, so here is a guess. Both files you sent look fine, but there is one difference between your theme.inc.php and the default one. You have a couple of blank lines after your closing php tag, the ?> at the end of the file. It's possible that these blank lines are being interpreted as header information.[]/w3timages/icons/crazy.gif[/].
Like I said, I'm not sure, but everything else looks totally normal. So, you can try removing the blank lines after the closing php tag and see if that helps.
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Scream
WWWThreads Developer