Here's what I did:
I go to do a post and want to add a pic. Unknowingly, my pic is a bit too big, bigger than 128k. So it gives an error stating so. No problem, hit the back and re-attach a smaller pic. Doesn't work, it gives this error message:
"The upload folder is full. Please try a smaller file and/or contact an administrator. "
Even though the file is now well under the limit (68k), it gives this message.