ESX 5.1 config changes do not save

I have two identical servers.     http://www.memoryexpress.com/Products/MX39068

Both servers have 32GB RAM.

Both servers have 3xIntel PRO 1000 NICs, with an on board realtrek NIC.

I have identical USB sticks.     http://www.memoryexpress.com/Products/MX35131

I have VMware ESXi 5.1 Update1 | 25 APR 2013 | Build 1065491 installed on the USB3.0 stick.

I have one server using USB in a 2.0port for the host ESX 5.1

I have one server using USB in a 3.0port for the host ESX 5.1

Both boot up fine.

I use the administrative reboot option in the GUI.

When I make changes to the ESX config on USB 3.0port and then reboot, all the changes are lost.

When I make changes to the ESX config on USB 2.0port and then reboot, all the changes are still there.

Any ideas on why 3.0 fails and 2.0 works?

Thanks