We recently upgraded our Citrix environment to XenDesktop 7.1. We published Firefox, but only one user at a time can have the program open. When we try to run multiple sessions, we get this error message "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system."

We've had it published in previous Citrix environments with no problems. How do we need to configure Firefox in XenDesktop so that multiple users can run the program at the same time? Thanks.