Cannot power a virtual machine within a virtual machine

I have successfully setup and configured ESX3.5 to run under VM 6 WS but it appears that when I add a VM using the VI client to the ESX host I encounter the following error;

"you may not power on a virtual machine within a virtual machine"

I am sure there must be something to work around this as I am aware that others have gotten VMs to work under ESX 3.5 under VM WS 6.0. If there isnt then there wouldn't be any point for xtravirt to even document and acknowledge this procedure for testing an ESX environment.

Any help would be appreciated

TIA,

aikora92