In a similar situation trying to boot a 64-bit VM in Autolab.
I understand that in 5.1 the virtualised HV is already enabled on the host so the only changes are in the vmx file for the VM.
In my situation, the host is running 5.0. My understanding is in addition to settting the CPU/MMU option to the last one, the only other changse required are:
1. Add "vhv.allow = TRUE" is ESX host config file
2. Add "vhv.enable = TRUE" to the 64-bit VM
3. Reload the vmx file for the VM
That being the case, I have done these steps but no joy.
Ideas?