Windows 7: Flight Simulator 2004 , VATSIM and Windows 7 Ultimate x64

Hi,
I just installed Windows 7 Ultimate x64 on my new PC.
Previously, I have used Microsoft Flight Simulator 2004 (FS2004) with XP SP3 x32. I have flied FS2004 on VATSIM (the International online Flying network) very smoothly.

Since i have installed Windows 7 Ultimate x64 and got the latest update from Microsoft, all Peer-to-Peer softwares on my PC can not run. I can not have voice communication with other players on the network, text communication is fine. I have tried lots of way such as forwarding port on DSL router, ticking Admin's right for all needed files...Nonetheless, there is still no P2P voice communication at all.

Please help me to explain the problem and please kindly help me to solve it.



Many thank.