I've checked 2.0.16, it works fine but the template problem.
You'd better check around here (especially PHP_SELF)
include/common.php
if (file_exists('./xoops_version.php')) {
$url_arr = explode( '/', strstr( $_SERVER['PHP_SELF'],'/modules/') );
$module_handler =& xoops_gethandler('module');
$xoopsModule =& $module_handler->getByDirname($url_arr[2]);
unset($url_arr);
if (!$xoopsModule || !$xoopsModule->getVar('isactive')) {
include_once XOOPS_ROOT_PATH."/header.php";
echo "<h4>"._MODULENOEXIST."</h4>";
include_once XOOPS_ROOT_PATH."/footer.php";
exit();
}