The issue is due to browser cookies.  Here is what you will want to do:

1. Login to the client area and download a new fresh copy of the latest PHP Live! software.
2. Update your current PHP Live! system with the new files (the standard upgrade process by replacing the existing files with the new files).
3. Launch the browser and clear the browser cookies
   (for Google Chrome, there is an addon to clear the cookies for just the domain, example Edit This Cookie for Google Chrome).
4. Attempt to login as the operator.
5. Done!

If you continue to experience login issues after clearing the browser cookie, please contact tech@phplivesupport.com for assistance.