I'm having trouble signing in to MS Lync 2010 client. I have two laptops and need to have the same user credentials log into both, but never simultaneously. One of the laptops logs in flawlessly; the other attempts to log in and just says "Contacting server and signing in" forever. Both laptops are signing in from the same network switch in our building, same network; and both laptops are the same make / model running Windows 7 Pro. I can't understand what the problem is! I have tried copying two certicates over from the working laptop (one in Credentials Manager and the other in certmgr) but this makes no difference. I have also uninstalled the Lync client, removed the "Communicator" folder, and removed two registry entires related to Lync; then reinstalled, and no different. The Microsoft Lync remote connection analyzer test is a success. Any help?