I suggest taking a look at your html sanitization settings make sure html isn't allowed in markdown settings.
Next step would be to move the other 2 topics from that category and check if you still see broken markup.
Is there a plugin that uses the stopforumspam api to block spam registrations. I know about spambegone but I want something that uses the stopforumspam api to block at registration time so I don't have to delete spam registrations later.
I've opened an issue for it on the spambegone plugin page