Firefox 3.6 will still be supported with security updates for a while, so if you don't want to work on troubleshooting the specific problems, you can roll back. First, make a backup of your computer for safekeeping. To back up Firefox, see [https://support.mozilla.com/en-US/kb/Backing+up+your+information Backing up your information]. Next, download and save Firefox 3.6 to your desktop for future installation. http://www.mozilla.com/firefox/all-older Close Firefox 4, and uninstall it. Do not remove your personal data and settings, just the program. Then finally you can reinstall Firefox 3.6. Unless you have installed an incompatible add-on, it should pick up where you left off. If there are serious issues, please post back with details. Note: I haven't actually tried this myself! By the way, someone else just posted about a Lotus email problem: [https://support.mozilla.com/en-US/questions/814413 The Webmail version of Lotus knows keep giving the following error message: A problem has occurred which may have caused the current operation to fail. How do I fix this? | Firefox Support Forum | Firefox Help]. You might bookmark that thread for future research.