problemo amigos!

A friend of mine'zzz ventrilo is not working perfectly. He can hear everyone but cant talk for himself, even if he pushes the button! When he tested it in ventrillo he could hear himself and everything seemed normal and also if he try's it in windows everything works , but somehow we cant hear him. (its not the volume / right selected mircophone) And yesterday everything still worked fine and he hasn't installed shit since...

help my poor friend! Thx