If Firefox windows open off screen or are too large to use, you may need to reset Firefox's controls and toolbars.

1. Close down Firefox completely: At the top of the Firefox window, click the File menu, and select the Exit menu item.Close down Firefox completely: On the menu bar, click the Firefox menu, and select the Quit Firefox menu item.Close down Firefox completely: At the top of the Firefox window, click the File menu, and select the Quit menu item.
2. In Windows, click Start, open the All Programs list, and navigate to the Mozilla Firefox folder. In the Mozilla Firefox folder, select Mozilla Firefox (Safe Mode).Hold down the Option key, as you start Firefox.Go to your Terminal and run:

   firefox -safe-mode

   You may need to specify the Firefox installation path (e.g. /usr/lib/firefox-3.5).
3. Firefox should start up with a Firefox Safe Mode dialog.
   
   Note: You can also start Firefox in Safe Mode by clicking Start, selecting Run (or use the Start Search box in Windows 7 and Vista) and then entering the following in the text field:
   

   "%PROGRAMFILES%\Mozilla Firefox\firefox.exe" -safe-mode

4. Check mark Reset toolbars and controls.
   
   
   
5. Click Make Changes and Restart to restart Firefox
   
   
   
   
   
   

The Firefox window should appear at a sensible size and position.