HA Error ‘An error occurred during configuration of the HA Agent on the host’ & "Host name lookup failure" on ESX host

I had to reboot one of the two ESX 3.0.2 server that I have here.

Now the I get a HA Error ‘An error occurred during configuration of the HA Agent on the host'  when try to reconfigure HA.

I also notice that within the console of the same host if type "hostname -a" I get "Host name lookup failure"

I appear to still be able migrate VMs but clearly something is wrong somewhere, is there DNS config file I can check, I have allready check ed the hosts file and I can ping everything using both long DNS name and short hostname.

Or maybe there is dns service I can restart?

Thanks