Go to the Customize menu you mentioned already again and then in the panel which opens, click the button called Restore Default Set. Then click "Done".

You should be able to drag the + sign back to the toolbar to create a button when you open the Customize menu again afterwards.

If this answers your question, please click the Solved it button next to this post after you log in into the forum. This will help others searching for a solution to the same subject.

Thanks.

Thanks Xircal, I tried that but it didn't work. I couldn't move the "+" from the tab and although I could drag the "New Tab" icon to the navigation bar, clicking the icon when it was in the navigation toolbar didn't do anything.

Clicking of "File>new Tab" and CTRL+T don't produce a new tab either.

Perhaps it is a case of uninstall (yet again) and re-installing it?

The Ask Toolbar is probably causing not being able to open a new tab in the Firefox 3.6.13+ versions. Uninstall that extension.

There are a couple of places to check for the Ask toolbar:

• Check the Windows Control panel for the Ask Toolbar - http://about.ask.com/apn/toolbar/docs/default/faq/en/ff/index.html#na4
• Also check your list of extensions, you may be able to uninstall it from there - https://support.mozilla.com/kb/Uninstalling+add-ons

Ed has a good point. The Ask Toolbar will be located in Tools | Add-ons | Extensions. You can remove it in there.

Thank you both very much. Uninstalling the ASK toolbar did the trick. It is a pity that when one updates software things like the ASK toolbar creep in and get installed as well.

The Ask Toolbar gets installed with user consent. It usually comes bundled with 'free software' and if you don't watch what you're doing before you click "Next", it will appear on your system. See screenshot for an example.

I am still trying to figure out how that became an acceptable practice for "reputable" companies like Sun/Oracle and Adobe - "slipping in" un-requested toolbar add-ons that the user has to watchful for and then de-select that "option" to not have them installed. I am looking toward the day that HTML5 video makes Flash irrelevant as a "plugin".

That was my problem. I didn't expect something to be installed by default so I did not look at the screen properly and just clicked "Next"