Problem Saving network settings on Vcenter 5.5 Appliance on the admin page.

I have set up out Vcenter 5.5 appliance and was trying to add out AD server as identity source but i discovered that the hostname wasnt the full FQDN, so I logged on to the admin page the port 5480 page and changed the hostname accordingly but after rebooting the hostname just reverts.  Ive now found that none of the Network setting I change are saving as they revert after a reboot.  I even tried using DHCP as i set the FQDN on the DHCP server but the network setting would not change to DHCP, it lets me save the change but rebooting it reverts.

Any ideas why I cant get it to keep the changes applied?

Thanks

JK