No, this is the virtual ESXi host. I haven't made any changes on the physical host.
In case I've misunderstood or misexplained our setup, this is it:
PhysicalHost1 is hosting an Autolab vAPP (vSphere 5 AutoLab) and within which are several guest VMs, 2 of which are virtual/nested ESXi hosts, the remainder are Windows VMs (incl vCenter).
The log and VMX file provided so far are all from one of the nested ESXi hosts.
As it happens, I'll be attending a VMUG today, and will raise this there too