In some instances the McAfee Site Advisor has been implicated in such problems.

• see Not working Back button when link opened in new tab....
• for general causes see Bookmarks and toolbar buttons not working after upgrading

All of the other buttons in the navigation tool bar work. In fact, when you hover over them, they highlight. The back and forward arrow navigation ones don't. and don't respond when clicked on. It doesn't matter if 1 tab or 2 tabs are opened.

Do you have McAfee site advisor on your computer ?

Note the back and forward buttons will not do anything untill you have navigated within a tab or window. If you just start up and then open an additional tab there will not be anything to go back to. If on the other hand you start up and then whilst on your Home Page open another webpage in that tab or window the back button should go green and allow you to go back to the Home Page.

The article I linked to did not contain much information, its search summary is possibly useful:

Firefox 3 stores your bookmarks and browsing history in the "Places database". If the places database is damaged or if Firefox is unable to access the file for other reasons, many functions will not work. Symptoms include bookmarks disappearing or not saving, browsing history not saving and toolbar buttons such as Back and Forward not working. If you are having these problems, try the solutions listed below.

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If you are having a problem with the back and forward buttons not working then the advice in the linked article Navigation buttons like back, home, bookmarks and reload are missing about checking for interfering software and resetting toolbars and controls is worth following

I suspect the article I linked to originally is faulty, I have asked for it to be reviewed.

I don't have anything from Macfee. Even if I have gone a few pages, like in Youtube for example, and try to back up a page to see something again, nothing happens. Its like they are disabled or something.

I suggest you have a look at

• Fix "The bookmarks and history system will not be functional" error message
• and http://kb.mozillazine.org/Locked_or_damaged_places.sqlite

If resetting the toolbars and controls does not help the next step is to try renaming (that effectively deletes) your places database. If you carefully follow the instructions in the lnked article you should not loose too much information, because Firefox should recreate most of the information from automatic backups that it makes.

If however the problem is cause by other software interfering it my well re-occur again.