No sound generated from MATLAB (Windows 7)

Suddenly no sounds are generated from MATLAB or Simulink. I'm referring to the auto generated sounds during compilation error or at the end of simulation. I've checked all Java settings and appear good, even reinstalled the latest Java. These sounds were played correctly, but they suddenly stopped and I cannot figure out why. I'm running on Windows 7. Even noticed that MATLAB does not appear in the Volume Mixer screen, but I'm not sure if it was there before.

Any ideas where to look?