Jim, I'm not sure why, but it appears you are missing a trailing double-quote char after the name of the font.
IN your post I see
Code:
[FONT="BOOK] more stuff .....[/FONT]
when it should have the trailing " after the word BOOK.
Code:
[FONT="BOOK"] more stuff .....[/FONT]
Now why that " char is missing I can't explain. It seems to work fine for me. I also went back and looked at other threads, and noticed that I see " in many threads. The best I can guess is that not all forums on this site have been configured to allow HTML chars, and that's why we're seeing ", instead of ".
One thing that definately seems to cause this issue is using the "Preview Post" when making a post. If there is a " character, it will be converted to " by the preview panel. That might be a source of many of the errors.