Firefox usually tries to remember the size of the last closed "restored" window, so if you stretch the window out to a more normal size and make sure to close that one last, hopefully it will stick. If it doesn't stick, one of Firefox's settings files may have become corrupted. Renaming that settings file will cause Firefox to return to its default window sizes and also will clear any toolbar customizations. If you would like to try this: (1) Open your personal settings (AKA Firefox profile) folder Help > Troubleshooting Information > "Show Folder" button (2) Switch back to Firefox and exit the program (e.g., Firefox > Exit or File > Exit) (3) Wait a few moments for Firefox to finish updating files in your settings folder, then rename '''localstore.rdf''' to something else, like localstore-bad.rdf or localstore.old. Alternately, you can delete the file. (4) You're done with your profile folder and you can restart Firefox now. Does it solve the window size problem?