Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes).

• Don't make any changes on the Safe mode start window.

See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

I do not have any new add-ons and I do not see how an add-on can cause this problem. This is clearly a FF problem. Also if you look at the replies in this forum on others who are also unable to close the firtst tab - it is not an add-on problem, but a FF problem. If I have to work with-out add-ons, I'll switch to Chrome. I am using FF because I like the add-ons. If FF changed itself to not work with one of it's add-ons - it should then communicate to us, which add-on they are discriminating against and work with the developer to sort the problem out - as said it is since the FF update - FF has to address the problem and not expect me to waste hours in finding out what the problem is.

I have the same problem. I tried disabling extensions one by one and found that after disabling new tab home page this stopped but I had a new problem, the I am not able to go back to the previous page. I can only go forward. The back/forward button below the file in menu toolbar is greyed out. Any ideas?

This can be a problem with the file places.sqlite that stores the bookmarks and the history.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

On further attempts. I believe that my earlier post was not the correct description. What I have found is that when Firefox is closed with a web page open on its first tab, the next attempt to open Firefox will cause the symptoms that Lorraine was talking about earlier. After that back keys don't work. This is not an extension issue. I believe that this is a Firefox issue.