I usually have three tabs open; two for my Tumblr blog and one for other sites that I visit. Recently, one of my two Tumblr tabs has been messing up; I normally have one for my dashboard and one for my inbox on Tumblr, but whenever I start Firefox, I get two inbox tabs. I can get to my dashboard again easily, but I have selected under my Firefox general options that Firefox starts with the windows and tabs I had last time - which is my dashboard tab, my inbox tab and my third tab. I don't change my tabs to having two of the same before closing Firefox, either. I've emailled Tumblr about this issue and I have yet to receive a response from them.

Thank you so much if anyone can help me out.