Why do I only get sound on some applications on my Windows 7 PC?

Q  I bought a new Windows 7 laptop a little while back and on the whole, it’s been working fine. However, I find that sometimes sounds don’t play – though this only seems to affect certain programs.

For example, if I play a Youtube video in Google’s Chrome web browser, I hear nothing. But if I play the same video in Firefox I can hear the audio, as expected.

Incidentally, I only installed Firefox for precisely this reason: I’d much prefer to use Chrome but I find that I’m unable to play any sound when I’m using this web browser. Can you help?
Susan Brown

A  Windows 7 introduced the ability to control the volume of each running application independently, so we think this is the cause of your sound problems.

To rectify it, right-click the speaker icon in the Notification Area (at the bottom right of the Taskbar) and choose Open Volume Mixer: now restore the volume by using the relevant application-specific slider controls (or mute buttons).