OldFatGuy: I'm NOT saying this is why others are having this problem... Let me repeat, I'm NOT saying this is why others are having this problem, but I wanted to point out for info purposes only that this will happen if your post has problems with brackets [ ] such as one missing, or one bracket starting a command (like bold) but then the other bracket is missing, or especially when quotes are included and there is a mismatch between the quotes and /quotes.
Tarnicus: ^^ is the most common cause I've found
I too have to say the only time I've experienced this the posts included several quotes, though this was also before I installed the BarefootEssentials tool which cleared up some forum issues I was having.