skype kind of freeze during mid of online session (everytime)

My wife uses endea linux xfce.. in the mid of skype session, it freezes.. (but not all freezed), the audio from skype session still available, but she can't mute and unmute mic .. both time, after she muted her mic when no need, she can't turn it back on.
any idea how to troubleshooot ? or solve the problem ?
I have reinstalled the skype package twice, but still the same.

anybody has encountered such issue ?
Thx