Sorry to hear about this problem. One thing users have been reporting in recent months is that there is a non-visible window of Firefox staying open when they think they closed Firefox by using the X button on the last visible window. Because Firefox still has a window open, it doesn't quit, and for that reason, it doesn't restore the last session when you use the desktop shortcut, it just creates a new window. To get the closed window back, they have to use the menu. Either: * "3-bar" menu button > History > Recently Closed Windows * "Library" toolbar button > History > Recently Closed Windows * (menu bar / Alt+S) History > Recently Closed Windows If you can't get the closed window back that way, you can use Firefox View to check for a non-visible window. Here's how: Open Firefox View using either: * file drawer icon at the left end of the tabs bar * type or paste '''about:firefoxview''' in the address bar and press Enter to load it In the left column of the page, click Open Tabs. Firefox should present a box for each window, listing its current tabs. If there is anything you do not need, or can't see on screen, you can use the controls here to close it out. If you are not suffering from the above problem, then the next step would be to consider settings issues. Note: in general, it reduces problems to quit Firefox using the menu instead of the X button. Either: * menu button > Exit * (menu bar / Alt+F) File > Exit