did you try updating your sound driver?

EDIT: Also try turning off audio enhancements in the control panel for your sound card

>>All of the sudden my computer stopped playing music files
That happened to me too awhile back. Foolish me! I had turned off the power to the speakers

I have just started having this exact problem with my vista. if i hit play in winamp on any audiofile, it just doesn't play, and in windows media player i am getting the same error as you.
It's not a speaker problem of course, audio still plays for example on youtube or even when adjusting the computer volume. For some reason it will just not play audio files.

Have you found any solution yet brianmat?

I have the same problem with my Vista laptop. I can't play mp3 files and the sound does not work when playing a DVD. There are no problems indicated of any type in device manager and my speakers are connected. The problem first appeared after installing a new version of Itunes. I have removed Itunes but still can't play any of my mp3 files, even the sample files that came with windows, so I doubt it's a copy protection problem. The computer sounds work OK but the sound in skype does not work. I tried a system restore but don't have a restore date that predates the itunes installation. Any help would be greatly appreciated.

JUST TO GET A BETTER UNDERSTANDING when you click on the music files do they open the associated program but u hear no sound

the sound problem in vista is a regular problem around the glob.this is becouse the manufactures of motherboards didnt take care in makin new drivers for vista.you should download new versions of your sound driver and then update in control panel

If you haven't done so already, try disabling your motherboards onboard audio if it has it through the BIOS and through the device manager.

Compaq laptop, Vista Home, Windows Sounds Play fine! Streaming audio from intenet(flash based player works too!) Every file type I can try doesn't have sound. I tried all the new codec packs, CCCP, NIMO etc. Windows Media Player, Media Player Classic, VLC player, MPlayer Nothing can get sound from this laptop, .mp3 .mpg .avi DVD nothing. There is nothing wrong with the drivers on this machine because it plays the login welcome noise when you turn it on! This is really frustrating. Also when you adjust the volume you can hear it too.

This is speculation: I am working on this machine for another person, who put Limewire on it. This program was the only thing that was installed before the no sound crash. She removed limewire, and when she did it killed the sound. I think

codec packs = bad idea. I'm afraid you may have complicated your problem...

Just another note, sound drivers in Vista are funny things. Just because they play your login sounds and stream just fine doesn't mean they're okay. In fact, when I just got this computer earlier this year, I had a similiar problem, playing sound files was an iffy experience, and using enhancements was a non-no. It turned out that my drivers weren't quite ready for Vista, and updating fixed it all.

I don't know how to tell you to fi the slew of problems you may or may not have spawned if you installed those codec packs on top of each other, but at least try updating your sound card driver.

Just try it, it won't hurt.