I run Firefox 29.0.1 on Windows 7 (64 bit) and I get the "Firefox is already running but not responding. In order to open the program you must close the existing window." error. EVERY TIME I try to start Firefox. The posted solution works to start the program, but it is not a permanent solution. I go through the Task Manager and end the old Firefox process, then I can open a new window. While working, I can open multiple tabs and multiple windows, everything seems to (usually) work the way it should. Then after I completely exit Firefox, in order to open the program again I need to fix the SAME error again. Every time. It doesn't seem to hurt anything really, but it is quite annoying. I used to get this same error on some of the older Firefox versions but it was only once in a while. With the new 29.0.1 it is literally EVERY TIME I TRY TO RUN FIREFOX!!!! So, down to the big question: is there a permanent fix for this yet? Or will there be one included in the next version update? Or am I going to have to go back to Internet Explorer? I know I am not alone in this experience; i've seen several other users posting similar questions but none of them received satisfactory answers. So what's the story here, team Firefox?