I am not sure this issue is very easy to solve, but there is always a hope that it might be.
I have a friend, and he cannot connect to spacial chat, nor into a group conferance.
However he can connect in a one on one chat inside of SL. The oddest thing about this is he sees his white chat dot. He doesn't see ours however. Its as if he is connected to a completely different server.
I believe he has all the correct settings in his SL
( i went through his connections with him, including him reinstalling SL and deleting his user settings in the application data folder before doing so)
If anyone has any advice or help, please do. Thank you very much