Try the following solution.
Ask the user to access the server health window (Help > Show Server Health on Windows and Help > Show System Diagnostics on Mac OS), then to click Web Conferencing, and to provide that information to you. The window provides status information that helps you to analyze connection and configuration problems. Make sure that the Cisco Unified MeetingPlace Express server is running.
⢠Check that the user has entered the correct credentials in the Cisco Unified Personal Communicator account preferences. After the user re-enters the credentials, the application tries to reconnect.
⢠Ask the user to verify the URL. The user can click the Invite Participants button or look in the Cisco Unified Personal Communicator log file. Verify that this URL is valid and can be reached from the client computer
⢠Make sure that the Cisco Unified MeetingPlace Express server and Cisco Unified Personal Communicator are using the same protocol, for example, HTTP or HTTPS.
⢠Obtain a snapshot of the Cisco Unified MeetingPlace Express System Information Capture log, and send it to the Cisco TAC for assistance. For details about this log, see the troubleshooting information in the Cisco Unified MeetingPlace Express configuration and maintenance guide.
For further information click this link.
http://www.cisco.com/en/US/docs/voice_ip_comm/cupc/7_0/english/troubleshooting/guide/trouble.html#wp1091356