MSN Messenger 6.1

I have MSN messenger 6.1.0211. It works in all respects except that I cannot have audio conversation with the other party. The video works okay. The audio wizard test is okay. I have Symentiec anti virus installed. I have a PC to Phone “iConnectHere” (Delta three) installed which works well. Please help as to what is stopping the audio conversation from taking place. When I click “audio” on top it says “connecting to….” but then the line drops and audio goes off. Regards – Khushroo