[Krofh]

Ahhh, I see what's causing it... obviously, there will be no user called "username;1324" anyways, I'm really tired right now and don't have the patience to test it thoroughly, but this should work...
1) Go to your Plugin Manager in the ACP
2) Edit the plugin "Quote Notification" under newpost_complete
Add the highlighted code:

$kr_load = array();
$kr_text = array();
if (preg_match_all("/\[quote=([^\\\"\]]*?)\](.*?)\[\/quote\]/is",$post['message'],$matches)>0) {
	for ($kr=0;$kr<count($matches[1]);$kr++){
		//echo $matches[1][$kr]."<br>";
		$matches[1][$kr] = (strpos($matches[1][$kr],";")) ? substr($matches[1][$kr],0,strpos($matches[1][$kr],";")) : $matches[1][$kr];
		if (strtolower($matches[1][$kr]) != strtolower($vbulletin->userinfo['username'])) {

I did some testing on my boards, and it worked fine, though like I said it wasn't very extensive. Let me know if that doesn't work.