My zabbix server running on:

Debian 5.0 lenny.
Kernel 2.6.26-1-686
libssh2-1 1.2.2.1

When i start my zabbix server and activate a ssh item my server goes down and the log says:

zabbix_server:/home/# cat /var/log/zabbix-server/zabbix_server.log | grep 12636

12636:20091221:101331.412 In get_values()
12636:20091221:101331.412 In DCinit_nextchecks()
12636:20091221:101331.412 In DCconfig_get_poller_items() poller_type:0 poller_num:5
12636:20091221:101331.412 End of DCconfig_get_poller_items():0
12636:20091221:101331.412 In DCflush_nextchecks()
12636:20091221:101331.412 End of get_values()
12636:20091221:101331.412 In DCconfig_get_normal_poller_nextcheck() poller_type:0 poller_num:5
12636:20091221:101331.412 End of DCconfig_get_normal_poller_nextcheck():1261386815
12636:20091221:101331.412 Poller #5 spent 0.000129 seconds while updating 0 values. Sleeping for 4 seconds
12636:20091221:101335.412 In get_values()
12636:20091221:101335.412 In DCinit_nextchecks()
12636:20091221:101335.412 In DCconfig_get_poller_items() poller_type:0 poller_num:5
12636:20091221:101335.413 End of DCconfig_get_poller_items():20
12636:20091221:101335.413 In substitute_simple_macros (data:'system.run[du s /home/`date +%Y""%m"-"%d` | awk '

{print $1}']')
12636:20091221:101335.413 End substitute_simple_macros (result:'system.run[du s /home/`date +%Y""%m"-"%d` | awk '{print $1}

']')
12636:20091221:101335.413 In get_value() key:'system.run[du s /home/`date +%Y""%m"-"%d` | awk '

{print $1}']'
12636:20091221:101335.413 In get_value_agent() host:'srv_prod' addr:'192.17.1.1' key:'system.run[du s /home/`date +%Y""%m"-"%d` | awk '{print $1}

']'
12636:20091221:101335.469 Sending [system.run[du s /home/`date +%Y""%m"-"%d` | awk '

{print $1}']
12636:20091221:101335.638 Get value from agent result: 'ZBX_NOTSUPPORTED'
12636:20091221:101335.638 Item [srv_prod:system.run[du s /home/`date +%Y""%m"-"%d` | awk '{print $1}

']] error: Not supported by Zabbix Agent
12636:20091221:101335.638 In zabbix_log()
12636:20091221:101335.638 In DCconfig_get_items() hostid:0 key:'zabbix[log]'
12636:20091221:101335.638 End of DCconfig_get_items():1
12636:20091221:101335.638 End of zabbix_log()
12636:20091221:101335.638 End of get_value():NOTSUPPORTED
12636:20091221:101335.638 In DCadd_nextcheck()
12636:20091221:101335.638 In calculate_item_nextcheck (100100000030075,60,"",1261386815)
12636:20091221:101335.638 End calculate_item_nextcheck (result:1261386875)
12636:20091221:101335.638 In substitute_simple_macros (data:'ssh.run[p_ssh_cal,,,]')
12636:20091221:101335.638 In substitute_simple_macros (data:'root')
12636:20091221:101335.638 In substitute_simple_macros(data:NULL)
12636:20091221:101335.638 In substitute_simple_macros(data:NULL)
12636:20091221:101335.638 In substitute_simple_macros (data:'password')
12636:20091221:101335.638 In substitute_simple_macros (data:'cat /etc/passwd')
12636:20091221:101335.638 End substitute_simple_macros (result:'cat /etc/passwd')
12636:20091221:101335.638 In get_value() key:'ssh.run[p_ssh_cal,,,]'
12636:20091221:101335.638 In ssh_run()
12636:20091221:101338.638 Timeout while answering request
12629:20091221:101338.639 One child process died (PID:12636). Exiting ...

What is the problem?

Thanks!