Could you elaborate a little more on how the client was installed on the workstations, how the users log into the windows session (are they all using an identical account on each machine), and how are they joining the conference (clicking on a hyperlink, joining via nefsis.com, desktop shortcut, etc)?The error message you are receiving is shown when multiple users attempt to join a conference with the same unique identifier. This identifier is created the first time the conferencing client runs and the process which creates the identifier virtually guarantees that it will be unique.This unique identifier is stored with the rest of the Nefsis settings in the user's Windows profile folder. The location of this folder varies based on the version of Windows, but by default:Windows 2000/XP: %userprofile%\Local Settings\Application Data\WiredRedWindows Vista/7: %userprofile%\AppData\Local\WiredRedFrom your description, it sounds like these machines are imaged with the Nefsis conferencing client already installed, and all of the users log into the machine with identical accounts. When they go to join a conference via hyperlink or web browser, the client identifies itself to the server using the same unique identifier for each user. The first user with this ID will get in; subsequent users will receive that error message.You can force the client to recreate this unique identifier by deleting the CC_settings.xml file in the location listed above. Deleting this file on all machines should allow all of your users to enter a conference simultaneously.