Cannot upgrade firefox

Well hello everyone, I hardly drop in anymore except when I have a problem. So here is the latest:

I have Firefox 12.0. For several months it's been asking me to update, but it always fails and issues the following message:

I tried updating manually. The first time it kept trying to force me to accept the newsletter. The last time, it just generated this same message that I've been seeing with every prompted update.

Also I frequently cannot open firefox because there is already a firefox.exe process loaded and not responding. So apparently it doesn't always close in the background when I close it from the "X" button. Is this a bug that the new version fixes? I would suspect some malware wanted to keep it open for some malicious reason, but weekly scans with MBAM and ongoing scans by NIS 2012 do not detect any malware. I'm the only user on my desktop PC computer and am vigilant about keeping it clean and streamlined. All Windows updates are current up until this week's.
Any idea what may be the problem?
Thanks,
Rusty

EDIT: I should add: if Firefox.exe keeps getting stuck in the background, a reboot will cure it for a couple of days. Since Windows Seven, I have not rebooted every day whether it needs it or not, like I always did before, since the beginning of Windows time.

Thats a very old version -we are now on Version 15.

I would uninstall version 12, and then download and install version 15 from here:
Mozilla Firefox Web Browser

Regards,
Golden

Rusty,

You can export your Bookmarks. Click in History >Show All History and check out the Import and Backup option.

set up an xmarks account free, and keep all your bookmarks saved to the servers. you can access them from any computer by logging on to the site when away from your own computer and you can sync bookmarks between laptop and desktop for example.
any new bookmarks get synced to the server when you close the browser.
this way if you have a house-fire your bookmarks are still intact

http://www.xmarks.com/

also ,when you uninstall firefox you get the option to keep your profile, make sure you do then your settings and extensions ,passwords and bookmarks get saved for the new install

Rusty,

I think your security setup is excellent. For peace of mind, run an online scan using ESET.

Regards,
Golden

quite often i end up with a couple of firefox processes running when closing firefox , i then get a message saying firefox is already running when i try to reopen ff, i dont think it has anything to do with malware or viruses,i think its just a glitch.
for this reason i have task manager pinned to my taskbar so i can kill the processes easily.