Thank you for your response. When I reboot the Host server the drives show up again but then disappear within an hours time. I am using an HP branded install named "hp-esxi5.0uX-bundle-1.3.5-3'. I downloaded it in July. Whats strange is that I have installed it on 5 ML350 G6 servers. 4 of which I used the internal SD card and they work fine. It is only the 1 that I used the USB stick that has the issue. The 2 others that I have the same problem with are ML350 G5's that do not have internal SD so I had to use the USB stick. I will try the latest version of the HP ESX install and post the results.
Thank you again.