[Znaper]

Ok im fixed this BUG!
The Sound plays so long, till you read the message!

Search for the fowling code into your index.php:

$newpm=$DB_site->query_first("SELECT COUNT(*) AS messages FROM privatemessage WHERE userid=$bbuserinfo[userid] AND dateline>$bbuserinfo[lastvisit] AND folderid=0");

And replace it with this code:

$newpm=$DB_site->query_first("SELECT COUNT(*) AS messages FROM privatemessage WHERE userid=$bbuserinfo[userid] AND dateline>$bbuserinfo[lastvisit] AND messageread=0 AND folderid=0");

When you have read the message, the sound and the light bulb goes off.