We are talking about the 1.2.7 non Bata? If sol.
Make sure all of your C++ files are up to date.
http://www.microsoft.com/en-us/download/details.aspx?id=30679
Also DirectX although you most likely have it, some did not.
http://www.microsoft.com/en-us/download/dlx/default.aspx?id=6883
As far as the Sound in Multiplayer with Headphones that is an issue with the sound card not the software, software puts sound out the sound card controls what plays the sound (ie. speakers, headphones, surround sound system).