Database error in vBulletin 3.6.8pl2

[SVTCobraLTD]

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)
/forums/includes/class_core.php on line 274

MySQL Error  : 
Error Number : 
Date         : Wednesday, March 5th 2008 @ 05:56:02 AM
Script       : http://site.com/forums/showthread.php?t=4497
Referrer     : http://site.com/forums/search.php?searchid=60432
IP Address   : XXXXXXXXX
Username     : 
Classname    : vb_database

Any ideas on what this error might mean??