Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home4/maritim5/public_html/forums/libs/mysql.inc.php:22 Stack trace: #0 /home4/maritim5/public_html/forums/libs/ubbthreads.inc.php(88): sql->connect() #1 /home4/maritim5/public_html/forums/ubbthreads.php(41): require_once('/home4/maritim5...') #2 {main} thrown in /home4/maritim5/public_html/forums/libs/mysql.inc.php on line 22
Its quite simple really; someone upgraded PHP on the server. PHP7 does not have the mysql_connect function (as the mysql_ functions have been depreciated and replaced by their mysqli_ counterparts), and any scripts that rely on it will present this error (anything coded prior to PHP7 without MySQLi support); you'll need to either roll PHP back to PHP5 or upgrade to UBB.threads 7.7.x.
You'll probably also want to check any PHP scripts installed on your server as there are likely other scripts showing the same behavior.