There's no more audio when I play files on my computer? The video works fine.

Well, first things first: have you checked the volume control in Windows Media Player?

I have checked volume controls for everything, yes :)

Mmm… is there any message in the Control Panel about some sort of conflict with the drivers?

Try reinstalling VLC and/or WMP. Your codexes might also be out of date.

Try reinstalling the original audio driver, which may be OEM and not Windows.

If you download Spyware Doctor and Norton for free from Google http://pack.google.com/intl/en/pack_installer.html and run both of those it will tell you if her computer is clean.

First, restart the computer. If that doesn’t work, reinstall VLC. If that still doesn’t work, go to http://microsoftwindowscom.tt.omtrdc.net/m2/microsoftwindowscom/ubox/page?mbox=US_Windows_redir_downloads-browseOffsiteClick&mboxDefault=http%3a%2f%2fwww.microsoft.com%2fdownloads%2fdetails.aspx%3fdisplaylang%3den%26FamilyID%3d50dff28b-8e0e-4b15-99a1-0d7b9ff3b795 and download Windows Media Player for Vista. Install it, and that will force a reinstall, in a manner of speaking. If none of that fixes it, you can do a system restore before going factory reinstall so that your files are safe. And there is a chance that with Vista, you can re-install the OS without wiping all the files, but I’d have to check.

or it might just be the audio driver. just sayin’.

I actually left home today, but I’ll try to arrange for these things to happen over the week. Couple of thoughts though, if it was the driver, why would youtube and other video/audio from the internet work?

Second, I did indeed uninstall and reinstall VLC (I should have mentioned that in the description) but that didn’t help. As for anti-virus, she had AVG until today and I uninstalled that and installed Avast today instead. I did a full computer scan too. There’s no sort of control panel conflict issue thing.

I’ll update as I do/know more. Keep the ideas coming guys. Thanks for all your help so far!

Oh, if you have any audio then it’s not a driver issue. Now I’m thinking it might be a codec issue or a bad dll that’s not getting replaced when you reinstall.

I had a similar problems couple of months ago, see

http://www.fluther.com/disc/62952/weird-sound-problem-on-my-pc-when-playing-mp3-files/

K Lite codecs has its own Classic Media Player, so you have 3 media players on your computer. I installed K-lite mega codec on a computer that had WinDVD on it. K-lite crashed my Windows Media Player, and I had to take it off. There was a conflict with WinDVD.