possible factor that exposes this - large iowait periodically

debuglevel 4 :

4654:20110728:094058.878 Processing request.
4654:20110728:094058.879 Requested [system.swap.size[,pfree]]
4654:20110728:094058.879 Sending back [6.707052]
4654:20110728:094101.879 Processing request.
4654:20110728:094101.879 Requested [mysql.queries[insert]]
4654:20110728:094101.879 In zbx_popen() command:'echo "show global status like 'Com_insert';" | HOME=/home/zabbix mysql -N | awk '

{print $2}''
4654:20110728:094101.880 End of zbx_popen():6
4654:20110728:094101.953 In zbx_waitpid()
4654:20110728:094101.954 zbx_waitpid() exited, status:0
4654:20110728:094101.954 End of zbx_waitpid():26532
4654:20110728:094101.954 Run remote command [echo "show global status like 'Com_insert';" | HOME=/home/zabbix mysql -N | awk '{print $2}

'] Result [7] [4786432]...
4654:20110728:094101.954 Sending back [4786432]
4654:20110728:094103.881 Processing request.
4654:20110728:094103.881 Requested [mysql.queries[update]]
4654:20110728:094103.881 In zbx_popen() command:'echo "show global status like 'Com_update';" | HOME=/home/zabbix mysql -N | awk '

{print $2}''
4654:20110728:094103.882 End of zbx_popen():6
4654:20110728:094106.881 timeout while answering request
4654:20110728:094106.882 failed to kill [echo "show global status like 'Com_update';" | HOME=/home/zabbix mysql -N | awk '{print $2}

']: [3] No such process
4654:20110728:094106.882 In zbx_waitpid()
4654:20110728:094107.844 zbx_waitpid() exited, status:141
4654:20110728:094107.844 End of zbx_waitpid():26538
4654:20110728:094107.844 Sending back [timeout while executing a shell script]
4654:20110728:094107.844 Got signal [signal:13(SIGPIPE),sender_pid:4654]. Ignoring ...