Funny thing (and very annoying) – my FireFox 3.5.5 doesn’t save cookies anymore. It saves cookies until browser is running, but after I close it and open it again only those cookies that are meant to be save until ‘end of session’ are preserved. My cookie policy is ok ( cookies are stored until they expire ), cache isn’t cleared after I close FireFox and there are no sites on ‘Exceptions’ list. Clearing cache & purging cookies does not help at all.

Update: I finally found solution – just delete cookies.sqlite and cookies.sqlite-journal from %USERPROFILE%\AppData\Roaming\Mozilla\FireFox\Profiles directory.