Keep getting urgent message to download update and when clicked on it never finisihes downloading but continues until I lose it and exit Firefox.

Question

Update box appears off and on urging me to update Firefox. If I click update it shows the candy stripe pattern in progress bar inside box but never completes the download. The first time this happened, I was busy working on computer and didn't notice until maybe an hour later. I attempted to stop/cancel and it would not stop. I exited Firefox. The next time I opened Firefox the update box did not appear. It has now appeared off and on for maybe two weeks. Today I clicked more info and it took me to the M. Firefox site. As there is an update I thought ok, legit, see what happens. I clicked the box and it did the same thing. I escaped Firefox to make it stop.
I went to the M Firefox site and clicked on the download for 4.1, it took a matter of seconds as is normal.
What is with the update box and not being able to stop/cancel and not loading and the urgent message? Who sent it and what is going on do you think?

Answer 1

Thanks so much for the reply. However, the issue is not "how to update" or "how to update most easily". The issue is an update box kept appearing with the message "it is strongly recommended that you apply this update for Firefox as soon as possible." Upon clicking "Update Firefox" there was a problem.
I already went to the site and updated as I note above. But I see this as a glitch: someone has programmed an update box that doesn't work. Is the someone at Mozilla Firefox, and there is a bug, or is it someone not at Mozilla Firefox. If there is a security and stability update available, and the download doesn't work, you get suspicious. When you try to stop the supposed download and it won't stop, you get freaked.
Anyway, thanks for the reply, but it assumes the wrong question. The real question is if this is a legitimate update and the update box is legitimate then why does it not work properly? If it isn't legitimate, why is it appearing?