I’ve encountered such problems for several times. I don’t know why, but it just happens. Bad luck, maybe.
First of all, let me describer the syndrome, actually there are two syndromes:
- After launching the Firefox, the browser returns an error message:
firefox is already running, but is not responding…
- After launching the Firefox, there’s totally no feedback. At first, the icon will show up, and after a short while, it disappears.
So the point is: how to fix it?
Of course, everyone knows that you should check the answers which you get from Google. But this time I got no luck, either those guys problems are differ from mine or the answers didn’t work for me. But at least, you can have a try.
Open Terminal (Applications–Accessories–Terminal or simply hit Ctrl+Alt+T), enter
then reboot your Firefox.
Unfortunately, solution one didn’t apply to my problem. So I have to find another one.
Open Home Folder (Places–How Folder), show all the hidden folders (you can do it by hit Ctrl+H), find folder named “.mozllia“, find its sub-folder named “firefox“, delete it and try again.
Solution Two worked for me, So I hope it will also works for you. Good luck.