What's your computer system and Firefox version?

Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

I have windows 10 on a lenovo y410p and not sure where to find the firefox version but I downloaded the most recent one when i tried to reinstall so I'm guessing that's 63.0.3 according to the releases page.

I tried removing firefox from the list of allowed apps on windows firewall but it won't let me remove Firefox (C:\Program Files\Mozilla Firefox)

What happens? What is the exact error messages?

Sorry should have been more clear, when trying to remove Firefox from the list of allowed apps on windows firewall, the remove button is grayed out even after I clicked change settings. Although I have two instances of Firefox in the list of allowed apps probably because I tried to add it earlier. One is checked private and one public.

Trying to open firefox again just gives me the idle cursor then nothing happens.

Remove the other entry. Then try again.

The other entry's "remove" button is also grayed out unfortunately.

Start your Computer in safe mode with network support. Then try the firewall.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

So after restarting in safe mode with network support, I checked the list of allowed apps through windows defender firewall. The "remove" buttons are still grayed out for the firefox entries.

Hi, try ending the process in the Task Manager (Ctrl+Shift+Esc), then do a Clean Reinstall; this means you remove your Firefox program files and then reinstall Firefox. This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location. Use another browser to download Firefox from https://www.mozilla.org/en-US/firefox/all/ and save the file to somewhere convenient on your computer.

Now delete the Firefox installation folder which should be in one of the following locations -

C:\Program Files\Mozilla Firefox C:\Program Files (x86)\Mozilla Firefox

You can now double click the file you previously downloaded to install Firefox.

If that doesn't work, see if it will start with your security program (anti-virus) temporarily disabled - something in there may be interfering.

So I deleted files in C:\Program Files and C:\Program Files (x86) and then reinstalled Firefox. I also turned off windows defender real time virus tracking and then tried to start firefox in safe mode (hold shift and start firefox). Now it seems to work!

I turned on windows defend antivirus again and firefox now still loads so I'm not sure if it was the antivirus.

Thanks for the help.