Well apparently I can in this forum section. An error message on why it doesn't manage to post in a sub-forum would be useful. The option to delete your own posts more even so.
Update: it seems the problem is caused by inserting links. There's probably a minimum post count for links.
Yes, you can't post links below a certain rep limit. The other annoying one is quote codes, get those unmatched and it just hangs, then you lose what you typed. Welcome to the broken form!