Hello<!-- XXX you may wish to edit this greeting, and other parts of the response so that it is personalised to the question asked.-->, Certain Firefox problems can be solved by performing a ''Clean reinstall''. This means you remove your Firefox program files and then reinstall Firefox . This process does not remove your [[Profiles - Where Firefox stores your bookmarks, passwords and other user data| Firefox profile]] data (such as bookmarks and passwords), since that information is stored in a different location. To do a clean reinstall of Firefox, please follow these steps: '''Note:''' You might want to print these steps or view them in another browser. #Download the latest Desktop version of Firefox from [https://www.mozilla.org mozilla.org] (or choose the download for your operating system and language from [https://www.mozilla.org/firefox/all/ this page]) and save the setup file to your computer. #After the download finishes, close all Firefox windows (or open the Firefox menu [[Image:New Fx Menu]] and click the close button [[Image:Close 29]]). #Delete the Firefox installation folder, which is located in one of these locations, by default: #*'''Windows:''' #**C:\Program Files\Mozilla Firefox #**C:\Program Files (x86)\Mozilla Firefox #*'''Mac:''' Delete Firefox from the Applications folder. #*'''Linux:''' If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see [[Installing Firefox on Linux]]. If you downloaded and installed the binary package from the [http://www.mozilla.org/firefox#desktop Firefox download page], simply remove the folder ''firefox'' in your home directory. #Now, go ahead and reinstall Firefox: ##Double-click the downloaded installation file and go through the steps of the installation wizard. ##Once the wizard is finished, choose to directly open Firefox after clicking the Finish button. More information about reinstalling Firefox can be found [[Troubleshoot and diagnose Firefox problems#w_5-reinstall-firefox|here]]. <b>WARNING:</b> Do not use a third party uninstaller as part of this process. Doing so could permanently delete your [[Profiles|Firefox profile]] data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. <u>These cannot be easily recovered unless they have been backed up to an external device!</u> See [[Back up and restore information in Firefox profiles]]. <!-- Starting in Firefox 31, the Firefox uninstaller no longer lets you remove user profile data.Ref: Bug 432017 and https://support.mozilla.org/kb/uninstall-firefox-from-your-computer/discuss/5279 [Fx31] Windows uninstaller will no longer offer the option to remove personal data --> Please report back to say if this helped you! Thank you.

When Firefox opens with your home page, is "Restore Previous Session" available on the History menu or is it grayed out? Does it help if you shut down Firefox using Exit from the menu? In other words, either: * "3-bar" menu button > "power" button * (menu bar) File > Exit

Thank you jscher2000, I shut down using the power button from the 3 bar menu, and it appears to have solved the problem! I'll test it a couple more times over the next couple of hours to make sure, then mark as solved. Edit: tested a few times now and still appears to be working, even when I now use just the 'x' to close all tabs (like I usually do) and not shutting down through the 3 bar menu. Very odd that that was the fix for it - and certainly easier than reinstalling etc! Thanks again jscher2000! :)

My guess would be that an incomplete shutdown at some point caused some file damage. Using Exit from the menu gives you better odds of a clean shutdown.