Leah, it's happened to me when I've put the pound sign in a post, and when I tried to use the French accent grave over the e in seance. It just makes a really black mark on the post instead of the intended character, but when it happened, I just went back and modified my posts when it did that - taking out the special characters. I think it might have happened in using one of the smileys as well, but I can't remember exactly what happened, which one, etc.