You mentioned that you downloaded the most recent update manually and tried to install it. Was this on the server or on the clients? Also, did you use the self-installing .exe file or the .xdb file? If you used the .exe file, try the .xdb on the server (available here). Then, follow these instructions and you should be able to get the server to update. Once the server is updated, I suspect that the clients should update fine. If not, try uninstalling on one client. I know you had trouble before, but it should work now that you have reset them to the new server. Good luck.

A.J.