You probably need to install the sound driver (also called audio driver) which you can download from the Compaq support website here: http://www.compaq.com/cpq-country/cpq_support.html
Be sure to select your country or region at top right of that page before proceeding.
Compaq laptop, windows vista home premium, we have a red X displayed next to our volume icon. When we move the cursor onto the icon, we get "no audio output device is installed" We have done a restart but that did not change anything. Laptop is out of warranty so HP is no help. Can anyone help us with this? thanks!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic