My firefox won't create a new tab when I click on the tab. It will create a new window. It worked fine till this morning. I've rebooted several time to see if that would make a difference. It doesn't.

I can only create tabs by clicking on a link in an email or a program or a link in the window I am viewing. It will NOT create a new tab when I click on the tab to create a new tab, nor will it create a new tab when I right click on the tab & click on create a new tab. I'm used to using tabbed browsing all the time & it's driving me nuts. HELP! I have not downloaded any new updates on any software or downloaded any new software in the hours before this started happening. Just to clarify about my original question. I meant to say that firefox will create a new window when I right click & click on create a new window but will not create a new tab when I click on create a new tab. I think what I wrote may have been somewhat confusing.