Database Error v4.05

[CFN-1]

Almost daily now, I'm receiving notices of database errors that look like this:

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' (11)
/home/hydropon/public_html/includes/class_core.php on line 313

MySQL Error :
Error Number :
Request Date : Friday, December 2nd 2011 @ 10:34:53 AM
Error Date : Friday, December 2nd 2011 @ 10:35:03 AM
Script : http://www.hydroponicunlimited.com/forum.php
Referrer : http://www.hydroponicunlimited.com/forum.php
IP Address : 218.204.14.59
Username :
Classname : vB_Database
MySQL Version :

What the heck is this trying to tell me? How do I repair whatever is causing this?

Please, H.E.L.P.