Your user agent is '''corrupted by Fast Browser Search (FBSMTWB)''' and that identifies you as Firefox/3.5.5 see your user agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.1.5) Gecko/20091102 '''Firefox/3.5.5 FBSMTWB''' [https://support.mozilla.org/en-US/kb/Websites%20or%20add-ons%20incorrectly%20report%20incompatible%20browser#w_reset-your-user-agent reset user agent] and you have no more problem see also these pages and threads about Fast Browser Search (FBSMTWB in the user agent). http://help.fastbrowsersearch.com/ http://www.pccybertek.com/2009/05/remove-fast-browser-search thank you Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.