I've got I don't know how many thousand songs on my hard drive. Something in the neighborhood of 20 gigabytes, though. Almost all of them are ripped from my CDs so that I can play them in my car more easily (I've got an in-dash MP3 player) as I don't have to worry so much about fiddling with discs and ruining my originals or having them stolen. Your problem is, indeed, spyware/adware/malware, whatever you want to call it. Here are a few more helpful links.

http://www.microsoft.com/mscorp/twc/...y/spyware.mspx
http://www.doxdesk.com/parasite
http://www.cexx.org/adware.htm
http://www.spywareguide.com/
http://www.spywareinfo.com/
The following site contains a fairly thorough list of suspected rouge/suspect antispyware products as well as some good ones. It also contains good information on how to get help with a spyware infestation.
http://www.spywarewarrior.com/rogue_anti-spyware.htm

Finally, this last link I have found to have a pretty good walkthrough on removal of spyware. You will need to scroll down slightly to find the article.
http://www.short-media.com/review.php?r=132

Also, if you're taking media files around, you will be better off to take the original MP3s, not burn them to an audio CD and then rerip them at home as each conversion to MP3 will further lessen your quality.

Humphrey's description of how an MP3 works isn't exactly correct. When you zip a file, that's exactly what happens. MP3 actually works by using perceptual audio encoding and psychoacoustic compression. It works by analyzing the audio waveform itself. It then takes the information that you really can't hear (you only hear a small part of the music) for various reasons (too quiet, too close to another in frequency, etc) and throws all that out, leaving only what you can hear.

How Stuff Works explains it MUCH better.