This has been a nagging problem for a few months - sometimes working, sometimes not (I can't figure out when it works and doesn't work). Just recently the volume was stuck on a certain level but I was able to adjust Windows volume so it was more an annoyance than anything else. But after pressing mute on the Youtube volume controls, it is stuck on mute - I can't adjust the sound at all and so can't get any volume on any Youtube video. Youtube works fine in Chrome. I tried reinstalling Firefox and Adobe Flash Player, and also restarting the laptop - no cigar. Any ideas? I'm tempted to throw in the towel on Firefox altogether - this shouldn't be so difficult!