When I try to post I am getting the following error most of the time.

The following errors occurred with your submission:

The message you have entered is too short. Please lengthen your message to at least 10 characters.

I tried to reply to a thread with a quote and it gave me this error so I tried without the quote and it posted. I tried to post a reply in a different thread with no quote and it wouldn't go through.

In both cases my replies were much longer than 10 characters.

EDIT: And this one worked fine.