Well, I have experienced something of this nature several times, and I have really not understood how/why it does happen. Altcoinstalks forum does not really have a strict posting intervals, most times when I make a post in a particular tab, then I make another post in another tab, going back to the previous one to make another post, it will give me something like warning, that "......this IP address has just recently posted....." Something of this nature. What I do is, clear the tab and open another tab, and its cleared.