Weird audio problem.. Some AVIs and some online video.. very low voume audio

The thing is its not everything so I assume there’s some problem with my computer. Everything used to run fine audiowise. Suddenly some of the AVIs I have start playing muffly and quiet sounding and lots of stuff I watch online like some stuff from hulu.com is quiet even with the volume maxed out.

By process of elimination I don’t think its my actual speaker system because some files are just fine with the audio.

I run vista… if that matters.
Thanks in advance if anyone has any ideas.

What media player do you use?

If it is not every video, I would start to suspect that it is the content itself that may have poorly recorded audio. This is not that uncommon in a world where more and more content is produced and uploaded by amateurs.

If you can determine that a praticular video does infact have normal sound levels played on another computer, then perhaps check to see if you can playback stereo audio properly by panning right to left with a known good audio file.

It is possible that a video with mono audio may play at very low level if your speakers were only connected to one channel of the sound card.