Persistent black screen when launching - spent over 2 days trying to get it to work

[jimavet]

So, I've been playing FFXIV on my own computer for many months without problem. I just got the game for my GF and have been trying - for over two days without success - as I have been perpetually frustrated trying to get past the permanent black screen on startup. Interestingly, during one of my MANY attempts to tweak some variable in the below list of things I have attempted to do, I was able to actually get into the game one time - but that was the only time I got past the black screen, and as soon as I quit the game and tried to re-enter, I immediately met the black screen again - all without actually changing any settings in between.

I have researched online and tried everything that is within my power without success. Granted, I'm not highly PC savvy, but I've tried:
Resetting IE. Set frontier.ffxiv.com and ffxiv.com as trusted sites within IE.
Running the launcher as administrator.
Adjusting the settings within the FFXIV_BOOT file various different ways.
Turning off Windows Defender and Windows Firewall.
Uninstalled and reinstalled the entire game several times - including trying to download it from Square-Enix directly, from Steam, and from Amazon.
Updated DirectX files.
Flushed DNS cache.
Tried setting Chrome as default browser, and then back to Internet Explorer (v11).

She has a brand new Alienware laptop that is running Windows 10. Anyone that can help me get this figured out would have my sincere appreciation!