Sound problems?

I'm not sure if this is an hardware problem or a software problem so I'm posting this here. I installed some freebie demon earlier today and ever since my sound has had an echoing and hollow sounding quality to it. At first I thought it was just with that game and another older game I had been playing then I realized it was a computer wide issue. Every sound my computer plays sounds horrible, hollow, distorted, and kind of down a well kinda thing. I have no idea what I should do with this, I've never had an issue like this before. Any ideas any one?

 

Have you uninstalled the freebie Demo?
Is anything near your rig possibly causing interferance?

 

I uninstalled the demo and I don't have anything around that could be interfering that wouldn't have done it before then Is there any program I can download to get my stuff or a good way to fix common sound problems?