Data only every 5 minutes (should be 60 sec)

[just2blue4u]

I have a problem with zabbix_agentd on my localhost (the server itself).
My frontend is showing me no Data in the graphs from period 1h up to 15h. From 16h period (increasing), the graph is shown correctly.
When i switch to "values of specified period", i get the output shown below (for period 1h):
Note that these values have an interval of 5-6 minutes. Configured interval is 60s.

2006.Aug.03 11:03:41	0.7900
2006.Aug.03 10:57:46	0.5400
2006.Aug.03 10:51:49	0.5900
2006.Aug.03 10:45:45	0.4700
2006.Aug.03 10:39:53	0.6900
2006.Aug.03 10:33:55	0.4000
2006.Aug.03 10:27:35	0.5800
2006.Aug.03 10:21:45	0.5600
2006.Aug.03 10:15:45	0.8200
2006.Aug.03 10:09:15	0.2500
2006.Aug.03 10:02:48	0.1900
2006.Aug.03 09:56:07	0.4000
2006.Aug.03 09:50:29	0.3200
2006.Aug.03 09:44:26	0.3300
2006.Aug.03 09:38:11	0.5900
2006.Aug.03 09:31:47	0.6100
2006.Aug.03 09:25:57	0.6200
2006.Aug.03 09:19:55	0.5900
2006.Aug.03 09:14:19	0.7600

This values are the loadav(1 min) from localhost. So lack of system resources shouldn't be the reason for this.
My agentd.log says:

003662:20060803:103234 Timeout while answering request
003660:20060803:103834 Timeout while answering request
003661:20060803:104418 Timeout while answering request
003660:20060803:105018 Timeout while answering request
003661:20060803:105620 Timeout while answering request
003660:20060803:110217 Timeout while answering request
003661:20060803:110857 Timeout while answering request
003659:20060803:111557 Timeout while answering request
003660:20060803:112249 Timeout while answering request
003662:20060803:112852 Timeout while answering request

if i do "zabbix_get -s localhost -k system.cpu.load", i get the correct value at once.

Why do i have this problem? Please help me...