I get the following message when attempting to open some links. I don't know how to interpret this nor correct it. Please help. "A copy of Firefox is already open. Only one copy of Firefox can be open at a time."

Question

I see some threads (when I google this question) — but do not understand how to correct it. I have a MB Pro, OS X 10.7.1, not a developer — online all day every day managing a small business. Specifically I receive the message more often when attempting to open a link within a tweet (photo, website, other).

Answer 1

Most people are going to see that message as a result of not properly closing Firefox, and then attempting to reopen Firefox. This problem is most likely to occur on Windows Operating systems, less frequently on Linux and Mac systems but not unheard of on any system.
Because you are on a Mac, I am referring you directly to an article that has been reworded for each operating system.
: http://kb.mozillazine.org/Kill_application
To properly close Firefox on your Mac use "Firefox" button -> Quit Firefox, and not with the "X" in corner of window which simply closes the window and not necessarily Firefox.
When you get stuck as you have described you must Force Firefox to terminate as described at the end of the article:
Mac OS X
:Open Apple Menu and select "Force Quit". For Mac OS X 10.3 and later, you can also use the Activity Monitor found in your "Utilities" folder (Applications -> Utilities -> Activity Monitor).
<br><small>Please mark "Solved" one answer that will best help others with a similar problem -- hope this was it.</small>