This is very bizarre and a specific problem. Ever since I purchased a new HP laptop this has started happening regularly: I would open Firefox and watch a few YouTube videos normally. After maybe the 3rd or so video, ALL the sonud of my entire laptop would stop working. I'd check the volume control and it all shows fine, however I can't hear any sound from anything else, not from other browsers, not from the computer's own media players, nothing, even though there is no 'muted' icon showing on anything. The moment I shut down Firefox ALL the sound comes back straight away. This has been happening constantly and I've had this laptop for a few months now (it didn't happen on my old laptop). So yes, obviously I've restarted the laptop loads of times. It keeps happening.

What is going on??