Nested Virtual Machines

Hi

I am having an issues with the following configuration:

Host: ESXi 5.0

Guest Windows 7

VMware Workstation Version 9.0.2

When trying to power on a virtual machine in vmware workstation in the Windows 7 guest we get the following error:

Running Vmware Workstation in a Virtual Machine requires the outer virtual machine to be configured as a Vmware ESX guest operating system. You cannot power on a virtual machine until the outer virtual machine is reconfigured.

I have seen some conflicting resources on line on how to resolve this.

Any help would be great.

Thanks.