This has been an on-going problem for quite awhile now.
Every once in awhile [more often than I care to count], my sound will just randomly stop working.
No warning or anything pops up, it just quits working.
And then if I click on the volume icon in the system tray, it says
"There are no active mixer devices available. To install mixer devices, go to Control Panel, click Printers and Other Hardware, and then click Add Hardware.
This program will now close."
So, anyone know wtf is going on?
Oh, edit: It works just fine again if I reset my computer. But occassionally, and it is rare, I'll get the same stuff right at start up.
Try reinstalling the sound cards driver, or reverting back to an older driver.
Open up your case, and make sure that the card isn't getting too hot.
^^ Ye' what he said... make sure the drivers are installed correctly - you may also went to make sure the card isn't getting unplugged on accident, maybe a loose screw or something. If nothing else, buy a cheap $30 sound card.