Yesterday night, I was listening to iTunes, then shut my laptop, but did not turn it off, because usually I never turn it off [every couple of days] When I went on my computer this morning, iTunes had encountered a problem and needed to close. So I just did send error report.. Then I went to YouTube and clicked on a video. It was playing, but the sound wasn't working. Getting worried, I went to iTunes and clicked on the song I was going to listen to on YouTube, and it wouldn't work [well, it was playing, but I couldn't hear it.] So I checked my sound and the volume is all the way up, it's not on mute, and there are no headphones plugged in. Any help would be appriciated. Thanks!