Random Host Disconnects in virtual center

Hello

i just notcied that i get random ESX drop from the vcenter where they become unavaliable for about 4 seconds and than come back.

during that time the VM's existing on them become disconnected and monitoring software kikso offf a lot of alerts.

what alarm i get in vcenter is:

First Event Generated:Host is not responding error 2/23/2013 12:01:11 AM vm14

secod events follow VM's disconnecting...

than i get: Alarm 'Host connection and power state' on vm14 error 2/23/2013 12:01:16 AM vm14

i checked the uptime on the esxi and not seeing the actual host loose power at all.

Any help would greatly be apreciated