vBulletin Database Error!

[JohorBahru]

I just received an email from my site regarding some "vBulletin Database Error!"

but i don't understand the meaning.. could anyone please enlighten me

=========================================
Error 1
=========================================
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)

XXXXXXXX/includes/class_core.php on line 311

MySQL Error :
> Error Number :
> Request Date : Monday, February 16th 2009 @ 10:08:53 AM
> Error Date : Monday, February 16th 2009 @ 10:08:53 AM
> Script : http://XXXXXXXX.com/index.php?board=30.0;sort=views
> Referrer :
> IP Address : 72.30.79.87
> Username :
> Classname : vB_Database
> MySQL Version :
=========================================


=========================================
Error 2
=========================================
Database error in vBulletin 3.7.5:
>
> Invalid SQL:
>
> SELECT forum.forumid, lastpost, lastposter, lastthread, lastthreadid, lasticonid, threadcount, replycount, lastpostid, lastprefixid
>
> FROM forum AS forum;
>
> MySQL Error : MySQL server has gone away
> Error Number : 2006
> Request Date : Tuesday, February 17th 2009 @ 10:26:12 PM
> Error Date : Tuesday, February 17th 2009 @ 10:28:25 PM
> Script : http://XXXXXXX.com/
> Referrer :
> IP Address : 202.156.8.246
> Username : Unregistered
> Classname : vB_Database
> MySQL Version :
=========================================

I've received a few emails for error 1, but with different url for the "Script "
anyone know the reason due? but my site is working fine even receiving this error
thank you

[Dismounted]

<a href="http://www.vbulletin.com/docs/html/troubleshoot_mysql" target="_blank">Troubleshoot MySQL Issues</a>