Try running Firefox in Diagnose Firefox issues using Troubleshoot Mode. If it functions properly in that configuration, then one of your add-ons is the culprit.

Running FF in safe mode was one of the steps that the FF help page said to do. I ran FF in safe mode as directed (as well as completed all of the other steps on the FF help page), but nothing has fixed the problem.

Any other suggestions?

The toolbar was removed in Firefox 4 although you can add custom toolbars.

Right clicking the Back/Forward bars will bring up a list of sites previously visited provided they take place in the current session. Also, provided you haven't configured FF to clear history on exit.

Sometimes it needs a little kick to get it going. So hit CTRL+H to open history in the sidebar, then change View to Last Visited.

I'm not sure about the two windows stacked on top of one another. Can you upload a screenshot?

I changed the view on in the history to last visited, but that had no effect on the back and forward buttons. Right clicking on the back and forward buttons does nothing. They are dead.

If you tell me how to send a screenshot, I will do so.

Thanks for continuing to try!

To take and upload a screenshot, hit the PrtScrn key and then open Windows Paint. Hit CTRL+V to paste it. Then use the right of the top two tools (looks like an dotted outline) by pressing and holding down the left mouse button while you drag it around the image you want to save.

Next, right click within the selected area and choose "Cut".

Next, go to File | New, click "No" to the prompt "Save changes to untitled?" which displays a blank screen again. Then hit CTRL+V to paste it again.

If there's a lot of white space surrounding the screenshot, grab the bottom right hand corner with the double-headed arrow tool and drag it to fit the image.

Then go to File | Save As and give it a name. Then in the field immediately underneath that, change "24-bit bmp" to PNG in the drop down menu.

Finally, go back to your post and underneath it, click Browse and go to the folder where you saved the image and click Open.

Windows saves it to the "My Pictures" folder which is contained in the "My Documents" folder by default, but you can save it anywhere you like, though preferably not in the Windows directory.

Here's the screenshot showing the stacked FF windows. Note that the minimize close button (X) doesn't work on the bottom of the two stacked windows.

Also, I thought I should add that before starting this post, I uninstalled Firefox altogether, then downloaded it anew because of these problems, but none of the problems were resolved by reloading it.

Any further thoughts on the disabled back and forward buttons?

Can you go to View | Toolbars | Customize. A panel will open where you can drag anything you don't want in there. You can also add to the existing layout from there.

But while that panel is open, you can also move things around. Is it possible to move that 'second screen'?

Interestingly, I was able to open View, Toolbars on the first try (and there was no way to deal with the second window or toolbar there), but after closing it, all of the menu buttons became disabled again. They were working, and only the back and forward buttons were disabled, but now all of the menu buttons and the back and forward buttons are disabled.

So now I still have stacked windows and no functional menu buttons.

How did you upgrade? Via the help | Check For Updates menu, or did you download it from Mozilla? If you downloaded it, did you delete the Mozilla Firefox Folder in C:\Program Files\Mozilla Firefox first or not?

I uninstalled Mozilla Firefox, using the add/remove programs tool in the control panel. Then using IE, I downloaded Firefox from scratch.

But you didn't remove the Mozilla Firefox folder presumably. Most people don't because they think it will delete bookmarks, but those are stored elsewhere.

Can you check in C:\Program Files and see if there's a Mozilla Firefox (2) listed there?

Also, can you go to Tools | Options | Advanced | General (tab) and uncheck "Use hardware acceleration when available".

There is only one Mozilla program file listed in C:\Program Files. Indeed, because my intent was to wipe out Mozilla completely, I was surprised when the bookmarks came back up in the reinstalled version. But there is only one Mozilla, no duplicates.

I unchecked "Use hardware acceleration when available." What does that do?

Hardware acceleration uses the graphics card's processor instead of the main CPU to display animations, video etc., but may not be suitable for all systems.

Can you restart FF to see if it made any difference?

I restarted FF, but no difference in the back and forward buttons, which are still disabled. The menu buttons (file, edit, etc.) are working, but only after I manually check Menu Toolbar after startup.

I'm ready to throw out this new version, as trying to do internet research is impossible without a back button. Do you know where I can download the previous version of FF, which worked fine?

You can get it from here: Download Firefox v3.6.16

But when you uninstall, make sure you remove the Mozilla Firefox folder in Program Files before you install it.

Will do. Thanks for all your help. Maybe the next FF version will be better for me.

You're welcome.

I wanted to let you know that I kept messing around to try to get FF 4 to work. I removed the Yahoo toolbar (I'm not sure how I installed it in the first place), and voila! Both the problem of stacked windows and the dysfunctional back and forward buttons went away. FF 4 is working fine, now. Thanks again for your efforts.

Well, that's strange because I suggested you run Firefox in Safe Mode which should have disabled the Yahoo toolbar. But you said you had already and it hadn't made any difference.

Using Firefox 4 I have the same issue with the back button being "dead" (at times). I have read the string to this point and will reinforce the other users complaint. I never experienced this issue with any previous version of Firefox.

One difference that I experience is that the back button usually functions correctly but sometimes does not. I don't have issue with the forward button but I rarely use it so it may be malfunctioning and I don't realize it.

I can also confirm that my history functions correctly in spite of the back button malfunction. This is how I get around the failing. I go to the history sidebar and select the site that I was just at (even though the back button doesn't show this).

I cannot reinforce the complaint about double loading of the tool bars.