Have two ESX 4.0 servers (identical HP DL380 G5) connected to shared SAS datastore. Have three VM configed. Created a cluster and turned on HA. Everything is reporting as fine (able to ping hosts, verified DNS, no errors). VMotion works fine and I can migrate VM from one machine to the other. If I test HA (unplug NICs) - the VM's do not migrate and restart as expected. Have walked thru every HA guide I can find (created HA enabled cluster first and then added hosts to it). The only thing that I see is that at the point the server goes off-line vCenter records "HA agent has an error: HA agent has failed" - this is at the point that I would expect it to migrate. Any ideas?