Problems started a couple of days ago when the cut scenes in Avatar The Legend of Korra video game would play without sound. I could hear the audio in the menus and in the game itself, but during the FMVs there was no sound. When I then tried to find the videos on YouTube using Firefox, I was again able to watch the videos, but could not hear any audio. I initially wondered if it was an issue with the videos themselves, but after reading comments that directly referenced the sound I realised the issue was with my computer. Since then I have lost audio in nearly every piece of software I have installed on my computer, including all of my games, my media players and Firefox. Bizarrely, however, When watching videos on Google Chrome I am able to hear the sound, and when I play flash content on Firefox, I also get sound. Windows sounds also work. I don't believe this to be a driver issue, as the problem persists between my USB DAC that I typically use for audio playback and my on board sound card, and updating/reinstalling the drivers for both had no effect. The other things I've tried have been fiddling around with the advanced audio settings, double checking that programs haven't been accidentally muted, reinstalling my codec packs and my media players. Windows troubleshooter has not found any issues, and all of my devices are showing as functional in Device Manager. All the common troubleshooting steps have failed me up to this point, and the fact that I'm still able to get audio from some software just seems to further reinforce the fact that this is either a completely obscure problem, or else something imperceptibly obvious. Any suggestions that doesn't include completely reinstalling Windows or upgrading to Windows 10 would be greatly appreciated.