Had a strange one after deploying an XP VM from a template today - the VM would not power on and threw the following error:
An error was received from the ESX host while powering on VM [VM name].
cpuid.coresPerSocket must be a number between 1 and 8
Digging around on google the error seemed to be related to over-allocating vCPUs (e.g. assigning 8 vCPUs on a VM with 4 physical CPU cores).