Host is unreachable, but new data is coming and Z is green

[xofer]

Now i have a host that is constantly "Unreachable" on dashboard. At the same time new data comes from the agent and the Z icon is green (!).

Zabbix server: 1.8.2 on Centos 5.5
host in question: Zabbix agent 1.8.2 on w2k3, default Template_Windows items and triggers

I can, of course disable the "Server {HOSTNAME} is unreachable", but then i obviously do not get any alarms when the server actually is unreachable.

Any ideas?