Ubuntu purple screen of death.

So I just installed Ubuntu 18.04 and it was working fantastically until this. Now, after I log in, all I get is a pure screen. I did dual boot, and windows still works.

The only thing I did differently was to try to change the boot order so that Windows would be the first option and Ubuntu to would be the second option, but when I did that I didn't get the option to choose which operating system I wanted to run, so I switched back to a ubuntu to load first and windows to load second and after that the problem appeared.

Any ideas what would cause this so I could avoid this trouble in the future, and does anyone know if there's a way to fix it so I don't have to try to remove Ubuntu and reinstall?