how to check your server from error

[member]

hi all
i have more then 5 month and iam trying to figure-out whats the problem with my server but nothing
i always get the error message (BLACK ZONE, YELLOW ZONE, GREEN ZONE) almost every sec since the first time i enter to this server i got those error:
shmpages
numothersock
numfile
kmemsize
and much more

More then that there is no one on the site there is no visitor even they come they can't because the page will take forever to load
until i restart the server
iam sorry for the long dis-court

i jusr really didn't now whats the problem or how to fix it, and my hosting provider he said i dont fix software problem

is there anything that can tell me whats wrong or check the server for error.
any ideal iam really lost here (i know iam noob, but iam trying).

i have VPS
CentOS 5.2
Virtuozzo & Plesk 9.2
Dynamic memory 1 Go
Mémoire garantie 256 Mo
-----------------------------------
details about the processor
http://paste2.org/p/358186
------------------------------

Database Version: 5.0.79 (mysql)
Database Collation: utf8_general_ci
PHP Version: 5.2.9
Web Server: Apache/2.2.3 (CentOS)
Web Server to PHP interface: apache2handler
XCache : 1.2.2
--------------------------------------------------------------------

Linux domain 2.6.9-023stab048.6-smp #1 SMP Mon Nov 17 18:41:14 MSK 2008 x86_64 x86_64 x86_64 GNU/Linux
--------------------------------------------------------------------

kernel-headers-2.6.18-128.1.10.el5
-------------------------------------------

Most error:
- the web site is very slow it take forever (only me on the site no others visitor)
to make it a little bit faster i had to restart the server

- after a while from reinstalling the os i can't access to plesk at all i recive (500 - Internal Server Error).
before restarting the server he fix the error but now nothing.

- restarting the server :
sometimes i get : field
or the database will load 15min after

those all th repo i have:
CentOS-Base.repo http://paste2.org/p/358334
CentOS-Media.repo http://paste2.org/p/358335
atomic.repo http://paste2.org/p/358338
atrpms.repo http://paste2.org/p/358339
centos-third-party.repo http://paste2.org/p/358340
mirrors-rpmforge http://paste2.org/p/358341
plesk.repo http://paste2.org/p/358342
rpmforge.repo http://paste2.org/p/358344

-------------------
sw-cp-server log:
http://paste2.org/p/360563

thanks.