Uninstall the Ask toolbar and it should work again. There is a compatibility issue with the Ask toolbar and Firefox that prevents new tabs from being opened.

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

When you click to open a new tab, you'll get a blank page which, you'll have to enter in the address bar exactly the page you want to display. If you go to customize your toolbars, there you can select to add the Open a new window icon/command. When you open a new window you get the Firefox home page, when you manually open a new tab you get a blank page, as I stated above.

Thank you TonyE!! it worked. I have been having trouble since that installed, I should have connected the two but didnt...

I already had removed ask tool bar and I still cannot open a new tab when i click it. Please help.