m4a files keep degrading

[Canis]

I ran AVG, Adaware, and Spybot, and didn't find any virus or other harmful whatever. I'm not sure how to check for hard drive failure, but I haven't had any other problem.

I've included a Hijackthis log, and here's a link to a zipped file containing one of the damaged m4a files. http://www.sendspace.com/file/st3b98 The skip is at second 17.