For a test, make a new Windows user, login to that new account and try there. If that's OK, it's not the program, but the Firefox profile in appdata\local and appdata\roaming. Simply rename or delete those folders, and it will go as well as in that new Windows account.
After this, you can delete that new Windows account again.
Since the update this week, Firefox won't load. I've uninstalled and reinstalled multiple times with no change. Suggestions? I seem to recall this happened before a long time ago, but I have no idea what to do to get Firefox to work again. Thanks.

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