Firefox 88 is compatible with Windows 7.

What makes you think it is not compatible ?

• https://www.mozilla.org/en-US/firefox/88.0.1/system-requirements/

It is possible that your firewall or other security software blocks or restricts Firefox without informing you, possibly after detecting changes (update) to the Firefox application. Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/en-US/kb/server-not-found-connection-problem
• https://support.mozilla.org/en-US/kb/Firewalls
• https://support.mozilla.org/en-US/kb/fix-problems-connecting-websites-after-updating

Hi Chris, have you tried doing another system restart in case there is some odd transient glitch?

Although I don't know why it would suddenly turn on, could you check to make sure Firefox is not executing in backwards compatibility mode? Right-click your Firefox desktop icon, or right-click your pinned Firefox Taskbar icon and then click Mozilla Firefox. Switch to the Compatibility tab and make sure Firefox can run in Windows 7 mode, and isn't forced to run in Vista or XP mode (which definitely do not work). Basically, make sure nothing is selected on the Compatibility tab.