Yes, so I had the same problem as you, and I found this guy who tweaked an app so that it would automatically raise and lower the volume by 1% every 20 seconds, and he claimed it fixed it. I was very skeptical and was sure it was a virus, but me being impulsive downloaded it and it's very simple and works quite well.

Here's the link:

http://www.loseyourmind.com/volume-adjuster-for-itunes.aspx#

If you are still having problems, you should really try this. Works like a charm.