It was working just fine lastnight before I turned my laptop off, but when I turned it on earlier, I wasn't getting sound from my programs. I get the boot up sound, and when I press the volume down or volume up buttons on my keyboard, I get the sounds. I went through all my programs to check if the audio was working correctly on any of them and the only ones that are working are Google Chrome and Quicktime player. VLC, iTunes, etc, aren't working, and I don't know why. Please help.