I'm having a problem with Firefox. I can't quit or force quit the browser. I used the red button on the browser window to close it; but, still can't get it to quit and now I can't reopen the browser. I tried to restart my computer thinking that might force Firefox to quit; but, it did not work and the computer canceled the shut down process. I've never had this issue with Firefox before. I can't even say which version of Firefox I have. It is a newer version, though.

I did find a similar problem in a different thread; but, the thread was closed; so, I'm starting this one. Please let me know what I can do to fix this.