I had to set periods/buffer to 3 on my laptop (the
default was 2). I
don't think jack exited when I had the default setting on, but it got
lots of xruns and playback was *really* rough.
I also had to do this when I set up my production machine. Something
to do with the sound card I think? I think 2 and 3 are the most used.
Arve