If you are an administrator and you find you can't edit your site despite logging in properly, clearing your cookies and temporary internet files, perhaps using a different browser may help.  This issue persisted for the clerk of Stisted Parish Council, despite clearing her cookies, temporary internet files and even after her password had been reset.  She tried using Google Chrome instead of the usual Internet Explorer and hey presto - all editing rights had been restored!  You may find that using the Firefox browser has the same magic touch.