hi Skip,
I genuinely was trying to be helpful. I will spell it out for you a little clearer; update your mac and make sure you have the latest fixes.
Often a new build of a product like CHIRP will have issues on an older version of the mac, depending on many many factors.
You have a couple of choices: 1) download a earlier version of CHIRP and keep flying, 2) update your mac and retry with the current version of CHIRP, 3) after updating your mac ( and still having the same issue with CHIRP ) open a bug report.
The problem you are talking about is not a common issue; consequently, there must be something about your setup that is unique. That is very helpful if you'll think about it a bit.
regards, '73
marcus
W0MHH