I am also getting this same error since yesterday now I thought everything is fine yet like today again it appears every time I browse for posting, another topic to post, refresh. Well they said that this is normal and it does happen as usual. I just relax myself then it goes after a while Just be patience is all I need..
some times it happens when we opened so many tabs in one browser. or when our browser have so many cookies and caches, clear your browser cookies and caches, and try it again. I also faced the same problem on mozilla firefox, then I start using google chrome. and then every thing going good now..