With IE 8 as the browser, after a successful login, the main navigation page is not presented. Instead it cycles back to the login page. There is no error message about an invalid user/password and the audit list shows that the login succeeded. So it appears that the mechanism used by NetMRI to remember that the user is authenticated (cookie?) is failing for IE8. It works fine with Firefox 10 ESR.
I reported this in the old Netcordia forum a couple months ago. Are others experiencing this as well? If so, have you opened a case?