Yes, I had done what Brett said in ubb_lib_posting when I did the initial install, but the problem still occurs. I verified that the mod is installed properly and precisely, also.
I'm putting simple HTML tags (font size, center)in the "Forum Introduction" section in the CP Forum Summary Options.
Sometimes I can get the HTML to stay as HTML for a short while, but after a few posts are made in one of the forums by a VIP using HTML tags, the tags on the main page revert back to text.