Even though I did not post a message for entire day,
I almost always get the 360 second error while trying to post a message saying I just posted a message in last 360 seconds.
I have to try al teast 3 to 4 times in a day to post a single message.
I have the same problem when I when I first started. I believe that it is due to you logging out after you post. So the 360 seconds might count your active time and not real time...