FaceTime stopped Working on Mac

[cjd]

I installed and used FaceTime on my 2008 MBP running Snow Leopard for several months. However, since yesterday FaceTime on the Mac stopped working. As soon as I try to place a call it tells me "FaceTime failed". That happens with all contacts on my list and using either a wired or wireless internet connection. System software is up to date. No recent changes to the MBP or network. FaceTime works on my iOS devices using the same WiFi network. I tried restating the MBP but the problem did not go away. Before this happened, FaceTime intermittently has audio problems where my contacts stop hearing me and that sometimes resolved by restarting the computer. Other times the problem persists and I have to switch to iChat or Skype to finish the conversation. Does anyone else have similar issues? Any suggestions to resolve these issues?