I have verified that it is not the IE browser, as CHROME does the same thing.

Makes it quite impossible to add a user to the system...

After playing a little more, I have discovered where the issue appears to be located.

When you have the host settings option for RibbonBar, and you hold the mouse in the black header bar just above the menu tab buttons in the DarkKnight skin, the system will flash back and forth between red and black, and periodically you will see a link appear and then it disappears. It is trying to pain the fly-out menu but cannot.

If you can get to the host settings and set the option for IconBar, it paints the area above the menu buttons with the old Icon Control panel, and the flashing goes away. However, you still cannot get the Manage context menu for any of the embeded controls to show. This makes it impossible to get to settings, edit content, add users, etc.

have you checked to make sure all js and css files are loading properly?