I think is an issue with OS X 8. I have the same problem.

System Preferences > General > Uncheck "Close windows when quitting an application" works with some applications, but not with Firefox (at least for me).

I don't have the answer to how to make sure the Firefox window is always maximized when you start it up. It might reduce your pain if before maximizing the window, you first stretch it as large as possible so that Firefox remembers this as the "standard" window size for the next time.

Are you first closing all open windows (i.e. leave the menu bar visible) or do you use Firefox > Quit to close the Firefox application with all open windows?

Does this also happen if you switch to full screen mode (Command+Shift+F)?

I already unchecked that box before posting the question, because its written in other questions here and in the Apple Forume where i put this question for the first time

sorry, i don't undestand your question

cmd+shift+f works but i have to re-do this command every time i re-open the program, is that normal?

i have only 13, the windows is already streched as large as it can be, but thank you

You can check for problems caused by a corrupted localstore.rdf file.

• http://kb.mozillazine.org/Corrupt_localstore.rdf

Try to remove the Firefox plist file (org.mozilla.firefox.plist).

• http://www.macfixit.com/article.php?story=20060606082246983 How .plist files become corrupt and troubleshooting the results

Go to "~/Library/Preferences" and remove the plist file for Firefox (org.mozilla.firefox.plist)