Keep getting to many connections database errors

[owning_y0u]

I keep getting the following error

Database error in vBulletin :

mysql_connect() [<a href='function.mysql-connect'>function.mysql-connect</a>]: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
/var/www/vhosts/xxxxxxxx.eu/httpdocs/includes/class_core.php on line 313

Database error in vBulletin :

mysql_connect() [<a href='function.mysql-connect'>function.mysql-connect</a>]: Too many connections
/var/www/vhosts/xxxxxxx.eu/httpdocs/includes/class_core.php on line 313

the database has a connection limit set on 250 connections so thats not the problem (as we have max 75 connections at the sametime.
Cookie session times out after 15 mins so not a problem.

getting crazy as i get around the 50 e-mails a day about it.