Does the problem recur each time you completely exit out of Firefox and start it up again, or only when you shut down Windows and start the whole system up again? Either way, I think we should assume it's a bad add-on. Here's my suggested procedure for tracking down and cleaning up bad add-ons, hijackers, and ad injectors. I know it seems long, but it's not that bad. (1) Open the Windows '''Control Panel''', Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here. (2) Open Firefox's '''Add-ons page''' using either: * Ctrl+Shift+a * "3-bar" menu button (or Tools menu) > Add-ons * in the Windows "Run" dialog, type or paste <br><code>firefox.exe "about:addons"</code> In the left column, click '''Plugins'''. Set nonessential and unrecognized plugins to "Never Activate". In the left column, click '''Extensions'''. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions. ''Bear in mind that none of these came with Firefox, they are all optional.'' Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step. Any improvement? (3) You can search for remaining issues with the '''scanning/cleaning tools''' listed in our support article: [[Troubleshoot Firefox issues caused by malware]]. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case. (4) Check for a '''user.js''' file in your settings folder. That's an optional settings file Firefox uses at startup to override your saved preferences from the previous session. The following support article has a section on how to check for and remove the file: [[How to fix preferences that won't save]]. By default, Windows hides the .js file extension. To work with files accurately, I suggest displaying all file extensions. This Microsoft support article has the steps: [http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions]. Success?