[orban]

Okay, can you upload the original template_cache.php again BUT keep the

if ($vbulletin->userinfo['userid'] == 1)
if ($vbulletin->options['pbtc_enable'])
{
cache_templates_with_file_cache($globaltemplates, $style['templatelist']);
$globaltemplates = array();
}}

plugin? And browse a few pages. Still blank pages?

Are you running on a shared server?

This might be happening because there are too many users trying to write the cache files....and then sometimes empty files are being created.