An error processing this directive

[Dinocanid]

(Can't remember if I made a thread about this or not...)
It's been going on for a long time, but for whatever reason some threads will refuse to post. Whenever the submit or preview button is pressed, it will show a blank screen with the message "[there was an error processing this directive]". It has something to do with the thread's content, because it doesn't appear if the text box is emptied.
I have no idea what triggers this, but it is most likely to show up when:

• posting code (code, html, and PHP tags)
• posting long topics (tutorials, updates, etc.)

This isn't always the case though, sometimes it won't post shorter messages either. I attempted to re-post this topic in my game's update thread, but I couldn't get through the first section before the error appeared.
Is there some sort of filter on topics that blocks certain things, or is this just a bug?

[Abronsyth]

I've been having this issue, too. Cannot do long posts or edit long posts.

[Hall of Famer]

I see. I will investigate this and see what may be causing the errors.