New Server Crashing After Some Minutes - Mysql

Our new server crashes about every 30',causing high high load(80!)

After mysql restart,everything its ok.

System:
Dual Core @ 3Ghz
1GB Ram
Sata Drives
Centos 5
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My.Cnf config:
--

Code:
[mysqld]
socket = /var/lib/mysql/mysql.sock
safe-show-database
old-password=1
max_connections=500
interactive_timeout=100
wait_timeout=30
connect_timeout=30
thread_cache_size=8
key_buffer=32M
join_buffer=8M
max_allowed_packet=32M
table_cache=1024
sort_buffer=32M
record_buffer=8M
thread_cache_size=128
max_user_connections=30

thread_concurrency=4
myisam_sort_buffer_size=64M
query_cache_limit=2M
query_cache_size=32M
query_cache_type=1

old-passwords = 1

[safe_mysqld]
err-log=/var/log/mysqld.log
open_files_limit=8192

[mysqldump]
quick
max_allowed_packet=32M

[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates

[isamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_bufer=16M

[myisamchk]
key_buffer=64M
sort_buffer=64M
read_buffer=16M
write_buffer=16M

[mysqlhotcopy]
interactive-timeout
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Top Process,showing in whm and status2k:
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/usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql --user=mysql --pid-file=/var/lib/mysql/server3.zaxihosting.com.pid --skip-external-locking --socket=/var/lib/mysql/mysql.sock