Full Screen Mode crashes

[Nocte]

I'm new to P99, and have been setting up my UI to start playing again. I set the client to full-screen mode through the in-game menu, and my client immediately crashed and returned an error.

Now, when I log in, I crash at the character select screen, and I cannot log in to change the option through the same menu. Is there a way to set the game to run in windowed mode without logging in? If not, what's the fix?