User Agent bug related to update to Firefox 10
Firefox 10 no longer sends HTTP_ACCEPT_CHARSET header.
Tor Browser Bundle tor-browser-2.2.35-5_en-US.exe behaves in the same way, not sending this header, however its User Agent is the same as Firefox 5, which did send the HTTP_ACCEPT_CHARSET header.
This makes it much easier for websites to identify Tor users, and can also cause some confusion for browser sniffing and web statistics, thus possibly denying access for Tor users.
Easy resolution is to update the Tor Browser Bundle User Agent to the same one as Firefox 10. Based on the upgrade curve of new Firefox versions, majority of Firefox users will be running Firefox 10 very soon.