Solution for Windows Media Player 11 (Vista) skipping exactly 20 seconds before the end of each track

1. Go to Control Panel.
2. Find and open the "Sound" applet.
3. Select the audio output that you're using (likely "Speakers") and click on the Properties button.
4. At the top of the new window, find and select the tab that is labeled either Advanced, Enhancements or Effects (it appears to be different, depending on the system).
5. On that page, disable audio enhancements (or system effects). Don't worry; it doesn't appear to have any negative effect on audio quality. If that option doesn't exist and you do have an "Allow applications to take exclusive control of this device" option, disable that, instead.