We have an OCS 2007 environment but still have numerous users using the Office Communicator 2005 client. I've had a few complaints recently of the 2005 client dropping the first communication. A user will instant message another user and the user will never receive the communication. If they keep on communicating that session by sending another message it will get through, but that first communication doesn't arrive as if it's being dropped or filtered. Anybody experience this. RG