Hi, I have a serious problem on my server with MySQL server, it overload itself without any error in

/var/log/mysqld

What steps should I do to find out the problem ?

my.cnf is

[mysqld]
set-variable=local-infile=0
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
old_passwords=1

skip-bdb
set-variable = innodb_buffer_pool_size=256M
set-variable = innodb_additional_mem_pool_size=20M
set-variable = innodb_log_file_size=128M
set-variable = innodb_log_buffer_size=8M
innodb_data_file_path = ibdata1:1000M:autoextend

Please help, thx