Hi, You can check the installed version via '''Help''' ('''Alt''' + '''H''') > '''About Firefox'''. Your Firefox version is being detected on websites as 3.5.4 (please see the section on the top right). You can try to filter for the word '''useragent''' in [http://kb.mozillazine.org/About:config about:config], right-click on every instance and '''Reset'''. # In the [[Location bar autocomplete|Location bar]], type '''about:config''' and press '''Enter'''. The about:config "''This might void your warranty!''" warning page may appear. # Click '''I'll be careful, I promise!''', to continue to the about:config page. [http://kb.mozillazine.org/About:config_entries about:config Entries]

This article in the Knowledge Base has more background on the issue: [[Websites say that Firefox is outdated or incompatible even though it's the latest version]].