[CentOS] Virtual Machine Manager Doesn't see vmx flag

Finished installing CentOS 5.5 x86_64 on a new Dell tower workstation that has a quad core Intel processor and 8 GB of ram. BIOS has hardware virtualization support enabled. /proc/cpuinfo shows that all four cores have the vmx flag present.

I applied a lot of the National Security Agency guide for securing Red Hat Linux 5, testing the key applications I need as I went. At the end of the process I bring up VMM and it claims that the hardware doesn't support full virtualization.

I'm going to go back through the NSA guide today looking for settings that might have an impact. My goal is to find and back out 1 or more settings rather than start from scratch with a full reload.

Any ideas where I should focus my efforts?

Dave M