Holiday Lights uses QuickTime (made by Apple Computer) to play background music. One of the drawbacks of QuickTime is that if you have virtual memory turned on and your Mac is running low on memory, you can experience problems like this.

If you're using RAM Doubler, the problem is even worse. Not only will it cause sound problems with QuickTime, it can also cause QuickTime to crash (this happens with any QuickTime program, not just Holiday Lights).

You can probably avoid this problem by turning off virtual memory or RAM Doubler.

The real solution, though, is to buy more memory for your Macintosh. It's cheap these days, and your whole computer will seem much faster.

 
See also:
Why is the Music Box empty?
I've downloaded a MIDI file from a Web site, but it won't play.