This bug has been copied from bug #616033 and has been proposed to be backported to 5.5 z-stream (EUS).
Tested with latest firefox (firefox-3.6.7-3.el5) in rhel 5.5. I am able to connect to a rhev-m 2.2 userportal.
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2010-0651.html