I am plagued by "flood detected" messages when I am trying to post. I try to come every once in a while to bump some threads I am interested in, but it usually doesn't work to post anymore. What triggers this message? It is certainly not the timing since it can be weeks since I last posted.

In addition to the main message, there is a code debug error on the top of the page:

#0 error() called at [/var/www/gc/inc/filters.php:148] #1 Filter->action() called at [/var/www/gc/inc/filters.php:244] #2 do_filters() called at [/var/www/gc/post.php:846}
Error
An error has occured.
Flood detected; Post discarded.