The vCenter Server Appliance Web interface does not work in Firefox 14
In Firefox 14 or later, the Administration, Services, and Storage tabs do not appear in the vCenter Server Appliance Web interface. The Admin page appears but is blank. This prevents configuration of the Active Directory membership and other settings.
Workaround: Use another supported browser, or use the Firefox Extended Support Release, which is based on Firefox 10 and can be downloaded from http://www.mozilla.org/en-US/firefox/organizations/all.html
source:
.http://www.vmware.com/support/vsphere5/doc/vsphere-esx-vcenter-server-51-release-notes.html
While this BUG was exist in 5.0 and NOT been fixed for 5.1 as well...
They just brave enough to write it down: it is a "known issue"