"simultaneous database connections" help

[bosanci28]

i had some email coming from my site

this one:

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)
/home5/xxxxx/public_html/xxxx/includes/class_core.php on line 314
 
MySQL Error   :
Error Number  :
Request Date  : Friday, August 12th 2011 @ 04:27:17 AM
Error Date    : Friday, August 12th 2011 @ 04:27:17 AM
Script        : http://xxxxxxx.com/calendar.php?month=3&year=2007&c=1&do=displaymonth
Referrer      :
IP Address    : xxxxx
Username      :
Classname     : vB_Database
MySQL Version :

and my host said that the error comes from """simultaneous database connections" !,
and they said that for some reason there is something into the script that is not right...

and i have not a clue what!,

i have the latest installed ver 4.1.5 ,

any idea?

thank you,