ERROR: Your topic cannot be created at this time.

Hi all
this is my (new) website: http://psychiatryadvice.com

When someone attempts to submit a new topic the following message occurs:

ERROR: Your topic cannot be created at this time.

Under settings>discussion I do not have any words in the blacklist or comment moderation. I also disabled the most recent plugin I installed (btw creating new topics was no problem after I initially installed this plugin).

Any advice how to fix this please?
Thanks!