I think these are some bugs occur at least in windows... 1. There is no warning when trying to close 2 or more tabs. 2. It is not possible to deactivate the automatic update. After restarting firefox it is set to automatic update again. 3. You can not have a blank page, it is always set to "my home page" and the search engine in the middle of the page doesn't work at all. The bugs occur only if you are running firefox as an administrator and not using it as a standard user in windows operating systems. I have recently downgraded from firefox 16.0.1 to firefox 10esr because the firefox rapid releases cause only problems and are no longer reliable and now I discover another kinds of problems...