The Webmaster contacted me, which led to a series of test posts. The issue is Dragon Naturally-Speaking version 12, which I have installed on my computers. Regardless of whether or not I'm using Dragon, or even whether or not it's running, it would add a bit of code at the end of my posts. For some reason, this blocked you, but apparently no one else, from posting. A good question is, "Why you"?
Also, I'm sure I'm not the only person on the forum that uses Dragon 12, but I haven't heard of anyone else causing the problem.
Dragon 12 adds two add-ons to Firefox, my browser. One an enhancement and one a plugin. They probably have something to do with Dragon's ability to accept and implement spoken commands for Firefox to do something. Disabling these two ends the problem; I did not remove them.
Another question I have, and maybe some forumite knows the answer, is does Dragon add codes to other documents I produce? No point in asking Nuance; while Dragon is an excellent program, Nuance's support, as evidenced by some comments made on the Dragon forum on this very issue, is somewhat lacking.