Hey People,

Had my mac since September now but this problem has only just started happening. For some reason, the sound will work on some things but not on others eg, when I play a WMV file on windows media player, the sound wont work, but when I play it on quicktime, it has sound, but when I play an MPEG file, the sound wont work on quicktime?!
And the radio 1 widget doesnt have sound in the dashboard and some online games dont have sound!?! This is the first time its happend and its really bugging me.

Can anyone help?