Basically, if you have the direct PM link hack installed, this mod interferes with it. So I disabled the PM popup code when you access private.php (which you don't need anyway since you are looking at your PMs).
You find this in global.php:
PHP Code:
if ($hack_pm_total > 1) {
Above this, add:
PHP Code:
if (strpos($_SERVER['PHP_SELF'], "private.php" ) == false) {
Then, find:
PHP Code:
eval("\$headnewpm = \"".gettemplate('head_newpm')."\";");
Below this, add:
The PM code will not show up when you are at private.php, preventing the 2 hacks from interfering with each other.