Thanks Fat16lib! I fixed the while(1) loop yesterday and I had been playing with priorities but I never could eliminate the problems for the reasons you pointed out. I don't have time to work on the audio library right now, but in a couple of months I may start trying to tune it up for use with Chibi.
Also, thanks for pointing out that the system tick is only 1 mS. Somehow, I missed that important detail in the literature. 