Check the Target line in the Properties of the Firefox desktop shortcut (right-click context menu) to make sure that nothing is appended. --- See this article for some suggestions: Firefox says it's just updated every time it starts - how to fix See also http://kb.mozillazine.org/Preferences_not_saved and How to fix preferences that won't save How to set the home page: Firefox supports multiple home pages separated by '|' symbols

So what I have done, is to accidentally set two of the same home pages so Firefox opens the same page twice. How do I remove one? Nothing is appended in my desktop link.

I had the same frustrating problem and now I don't. When you want to access the internet, instead of "double clicking" on the Firefox icon, "single click" and you will open one page instead of two. Or you can right click your Firefox icon and click open. Either way it works.

I had the same problem. Solved it by starting Thunderbird in a safe mode (http://kb.mozillazine.org/Safe_mode), closed it and started normally... Thunderbird showed 1 window afterward... I did play around before that with disabling/enabling extensions but at the end the safe mode helped... Hopefully this helps someone :)

Thank you! An easy and perfect solution to my problem with two thunderbirds. I remained sceptical when two windows opened up in safe mode, too. But after closing them I only got one window in the 'regular' thunderbird. Thanks again!