منتدى استراحات زايد

Hi.
Since 2 weeks, I am having problems with mysql. From time to time, I am receiving mysql_connect error on email, and don't know what can cause this:
Code:
Database error in vBulletin :

mysql_connect(): send of 68 bytes failed with errno=32 Broken pipe
/home/.../www/includes/class_core.php on line 317

MySQL Error :
Error Number :
Request Date : Tuesday, October 23rd 2012 @ 03:35:15 PM
Error Date : Tuesday, October 23rd 2012 @ 03:35:38 PM
Script : ..../cron.php?rand=1350936301
Referrer : ...
IP Address : ......
Username :
Classname : vB_Database
MySQL Version :

It's not just cron.php script, but on every one.
Once I had error:
Code:
Database error in vBulletin 4.2.0:

Invalid SQL:

SELECT
userfield.*, usertextfield.*, user.*, UNIX_TIMESTAMP(passworddate) AS passworddate, user.languageid AS saved_languageid,
IF(displaygroupid=0, user.usergroupid, displaygroupid) AS displaygroupid,
language.phrasegroup_global AS phrasegroup_global,
language.phrasegroup_dbtech_vbshout AS phrasegroup_dbtech_vbshout,
language.phrasegroup_user AS phrasegroup_user,
language.phrasegroup_posting AS phrasegroup_posting,
language.phrasegroup_album AS phrasegroup_album,
language.phrasegroup_messaging AS phrasegroup_messaging,
language.phrasegroupinfo AS lang_phrasegroupinfo,
language.options AS lang_options,
language.languagecode AS lang_code,
language.charset AS lang_charset,
language.locale AS lang_locale,
language.imagesoverride AS lang_imagesoverride,
language.dateoverride AS lang_dateoverride,
language.timeoverride AS lang_timeoverride,
language.registereddateoverride AS lang_registereddateoverride,
language.calformat1override AS lang_calformat1override,
language.calformat2override AS lang_calformat2override,
language.logdateoverride AS lang_logdateoverride,
language.decimalsep AS lang_decimalsep,
language.thousandsep AS lang_thousandsep

FROM vB_user AS user
LEFT JOIN vB_userfield AS userfield ON (user.userid = userfield.userid)
LEFT JOIN vB_usertextfield AS usertextfield ON (usertextfield.userid = user.userid) LEFT JOIN vB_language AS language ON (language.languageid = IF(user.languageid = 0, 2, user.languageid))

WHERE user.userid = 147;

MySQL Error : MySQL server has gone away
Error Number : 2006
Request Date : Monday, October 22nd 2012 @ 09:57:03 PM
Error Date : Monday, October 22nd 2012 @ 09:58:06 PM
Script : ....
Referrer : ....
IP Address : ...
Username :
Classname : vB_Database
MySQL Version :

I have VPS in leaseweb, mysql version: 5.1.58-1-log
Could someone help me?
I have the newest vB 4