https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved You may have corrupt xulstore.json file.

Close Firefox. Open your file browser to this hidden location:

• Mac: *~/Library/Application Support/Firefox/Profiles
• Linux: *~/.mozilla/firefox/Profiles
• Windows: %AppData%\Mozilla\Firefox\Profiles
• *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles
• Windows XP: C:\Documents and Settings\<user>\Application Data
  \Mozilla\Firefox\Profiles\

Search for the above file. Then rename or delete it. Restart Firefox.

What security software do you have?

Can you bring up the system menu via "Alt+Space" ?

webroot secure anywhere complete

Hi jakecblake, when I click the Firefox Taskbar icon and the program is already running, Windows shows thumbnails for each window that I can click to activate that window. Does yours do that, or nothing at all happens at all?

jscher2000 said

Hi jakecblake, when I click the Firefox Taskbar icon and the program is already running, Windows shows thumbnails for each window that I can click to activate that window. Does yours do that, or nothing at all happens at all?

yes I see thumbnails but nothing happens when I click on them

jakecblake said

jscher2000 said

Hi jakecblake, when I click the Firefox Taskbar icon and the program is already running, Windows shows thumbnails for each window that I can click to activate that window. Does yours do that, or nothing at all happens at all?

yes I see thumbnails but nothing happens when I click on them

Does Windows show any kind of animation to suggest the window might be off-screen?

Sometimes the main Firefox window gets "off screen" somehow. You often can force it to appear on the screen by right-clicking the thumbnail image floating above the Taskbar and choosing Maximize. Does that work?

One possible cause for this is when the file which stores window sizes and positions has become corrupted. As FredMcD mentioned, you can remove that file and Firefox will return to standard window sizing/positioning.

Method #1: If you can get a maximized window:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then scroll down and rename xulstore.json to something like xulstoreOLD.json just in case you need it later. If you see a file named localstore.rdf, it's obsolete and you can delete it so Firefox doesn't convert it at your next startup.

Start Firefox back up again. Do windows display normally again?

Method #2: If you cannot get a Firefox window at all:

Shut down Firefox by right-clicking the taskbar icon > Close Window or Close All Windows.

Using the Run dialog (windows key + R) or the Windows search box, type or paste the following and press Enter to drill down to the Profiles folder:

%APPDATA%\Mozilla\Firefox\Profiles

Here you may see one folder -- in which case, double-click into that -- or more than one folder -- in which case, double-click into what looks like the most recently updated.

Scroll down and rename xulstore.json to something like xulstoreOLD.json just in case you need it later. If you see a file named localstore.rdf, it's obsolete and you can delete it so Firefox doesn't convert it at your next startup.

Start Firefox back up again. Do windows display normally again?

That mini-reset will hide the menu bar and bookmarks toolbar. If you like to display one or both of those bars, you can use any of the following methods to show the toolbar list and select the desired bars there:

• right-click (on Mac Ctrl+click) a blank spot on the tab bar (or right-click the "+" button)
• (menu bar) View > Toolbars
  On Windows, tap the Alt key to activate the menu bar temporarily.
• in Customize mode > Toolbars button (see: Customize Firefox controls, buttons and toolbars)

To turn on the Bookmarks Toolbar, Menu Bar, or other bars, click it on the list.

thanks for all of your awesome help