Hi, since it is OK in Safe Mode, the problem is most likely caused by an extension, theme or hardware acceleration. So please see this article - Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

It is possible that your firewall or other security software blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to install for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating