Virtual Machine may unexpectedly reboot when using VMware HA

Virtual Machines may unexpectedly reboot after a VMotion migration to an ESX 3.5 Update 3 Host OR after a Power On operation on an ESX 3.5 Update 3 Host, when the VMware HA feature with Virtual Machine Monitoring is active. A virtual machine may reboot itself when the following conditions exist. Virtual Machine is running on ESX 3.5 Update 3 Host, either by virtue of VMotion or a Power On operation, and a host has VMware HA enabled with the "Virtual Machine Monitoring" option active.

Virtual Machine monitoring is dependent on VMware tools heartbeats to determine the state of the Virtual Machines. With ESX Server 3.5 Update 3, after a VMotion or Power On operation, the host agent running on the ESX server may delay sending the heartbeat state of the Virtual Machine to the Host. VMware HA detects this as a failure of the Virtual Machine and attempts to restart the Virtual Machine.