Unity 5.6 won't start

I know this has been asked before, but none of the suggestions have worked so far. Unity 5.6.1f1 won't start. I get to the startup screen where I can choose a project, then it flashes the loading box just for a second and that's it. It shows it as running in Task Manager, but there's no editor on screen. I have disabled Malwarebytes, even disabled Windows Defender for a lark, tried working offline, uninstalled and reinstalled, installed to a different drive, nothing has made a difference. Windows 10, by the way. Thanks