Does the website work when running Firefox in Safe Mode?

Yes, it does! What do I need to open it in regular mode?

If it works in Safe Mode and in normal mode with all extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) disabled then try to find which extension is causing the problem by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via one of these:

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit

You can also check the Web Console for related messages.

• "3-bar" menu button or Tools -> Web Developer
• https://developer.mozilla.org/en-US/Tools/Web_Console

I think Firefox is what's causing the problem. Thanks for your time and everything but, really? Forget it.

If it works in Safe Mode, but not regular mode, it's very likely that it's an add-on causing the problem. The main thing that Safe Mode does is disable all of your add-ons, so if the issue disappears in Safe Mode, that's the reason.

It's likely that you have an add-on that you may not consider to be an "ad blocker" but might be detected as one. For example, an extension like Privacy Badger isn't really considered to be an ad blocking extension. However, since it may block certain "trackers", websites may believe you are using an ad blocker.