I do provide free support for all my modules!
This is due to me being awful at using isset when I built this many years ago.
If you change line 371 to the following it'll work fine, depending on what version you have their maybe other instances of issues like this.
$(this).html('<input type="text" name="userTo" size="3" value="<?php echo (isset($_COOKIE['user_for']) ? abs((int) $_COOKIE['user_for']) : $ir['userid']); ?>" style="font-size: 12px;font-family: Tahoma;padding:0;margin:0;text-align: center;" />');
Get in contact with me via Skype and I'll give you the latest version: oxydennet, providing you paid for it!