Finally today, I got tired of seeing the message so I did a little research. It turns out a CD ripping application I use, Exact Audio Copy, is generating the error each time it is closed. The solution is to put a more up-to-date copy of cygwin1.dll into the proper EAC folder. Fortunately, I already had a more up-to-date copy of that dll file, courtesy of a couple of other apps I use. So I simply renamed the older EAC cygwin dll (just in case I needed it back) and copied a newer cygwin dll into the EAC folder. Voila! Problem solved. No more error message. Honestly, I don't think it was a "problem" that actually made any difference. Nonetheless, I don't like error messages. I'm happy to have gotten rid of this one.
The link that helped me out is this one. That's my tidbit for today.