When trying to launch firefox like normal I got a "Your profile cannot be loaded. It may be missing or inaccessible" which would keep it from starting. Periodically, with firefox not even running in the background, I would get the XULRunner error (see attached image). Looking online for solutions I took two steps: 1. located my profiles folder and deleted it 2. reinstalled firefox entirely As you can see by the attached image the same error messages as before would actually interrupt the install itself. I am at a loss and any help would be appreciated since Chrome sucks and I'd like to keep using Firefox.