I've accidentally told Firefox to block graphics from some forum or other before, which resulted in a similar problem. Trying it on purpose now, this will make the Edit, Quote, Multiquote, and Quick Reply buttons disappear; only Fork to New Thread remains, plus the New Reply button on top/bottom of the page. (Telling Firefox not to load graphics at all, anywhere, will replace the buttons with links; telling it to load graphics but making EN World an exception to that rule will result in no buttons and no substitutes.)
So I'd check the settings for anything that might block graphics.