Find the following function in www/admin/lib-swf.inc.php (relative to your OpenX base install directory):
<?php function phpAds_SWFVersion($buffer) { if (substr($buffer, 0, 3) == swf_tag_identify || substr($buffer, 0, 3) == swf_tag_compressed) return ord(substr($buffer, 3, 1)); else return false; } ?>
And change that to:
<?php function phpAds_SWFVersion($buffer) { if (substr($buffer, 0, 3) == swf_tag_identify || substr($buffer, 0, 3) == swf_tag_compressed) { $rv = ord(substr($buffer, 3, 1)); if ($rv > 10 && $rv < 13) $rv = 10; elseif ($rv >= 13) $rv = 11; return $rv; } else return false; } ?>