One of the issues that we have found is that due to the changes that have been made in both vsphere and windows that volumes appear as hotplug devices in Computer Manager, also this can affect how disks are brought online by windows.
To resolve this add the following setting to the vmx file
1 devices.hotplug = "false"
Also within windows make sure your diskpart san policy is set to always on.
(This will then show your policy)
(and your done)