ESXi 5.1 triggers false "host not responding" alarms

Hi All,

Hope this issue might be old, i have esxi 5.1 host running on vCenter 5.5.

These days am getting many host not responding alarms, when i checked host is up and running.

i found somewhere to increase the heartbeat from default 60 seconds to 120 seconds., But still am getting the false " host not responding " alarms.

Did any one faced similar issue, Any help will be appreciated.