How would you feel about installing Firefox 23? You should be able to download and run the installer even if you can't run the update from withing Firefox 22.

Choose the file for your preferred language from the Windows column here:

http://www.mozilla.org/firefox/all/

Usually you do not need to make a backup before running the installer, but it's not a bad idea to back up the contents of your currently active profile folder. It's probably the one with the most recent modification date here:

%APPDATA%\Mozilla\Firefox\Profiles

By the way, have you restarted Windows since this problem occurred? If not, you might want to try that first.

Hey, I restarted it, and now Skype is working again, but both irefox and Thunderbird are still crashing the moment I try to open one of the programs. Updating Firefox also didn't help.

Is it possible that this crashing is due to certain malware?

Generally speaking, crashing could be due to malware. You may want to run some supplemental scans. These three tools are highly regarded (and free):

• Malwarebytes Anti-malware : http://www.malwarebytes.org/products/malwarebytes_free
• SUPERAntiSpyware : http://www.superantispyware.com/
• AdwCleaner : http://www.bleepingcomputer.com/download/adwcleaner/ (ignore banner ads for other products)

Another possibility is that your Firefox settings have become damaged in some very serious way. Can you try creating a new Firefox profile. In addition to bypassing current extensions and custom settings, it should have completely fresh settings databases and a fresh cache folder.

Close Firefox and start up in the Profile Manager as described in this article: Profile Manager - Create, remove or switch Firefox profiles. When you create a new profile, I recommend using the default folder location suggested; to avoid data loss, do not select any existing folder location. Also, before removing any profiles, I recommend backing up all of them just in case something goes wrong.

Will Firefox let you run the Profile Manager and, if so, does the new profile work?

Hello, also, try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) and check firefox again.

(If works in Windows Safe mode then probably you have problem with other software, like security software or maybe a system driver, that is running on your computer).

do you have Avast Antivirus ?

thank you

I ran Malwarebytes anti Malware and after another restart it seems to have fixed the problem. Thank you so much for your advice and help!!!