Starting with black screen

I have had krypton 17.1 set up just the way I like it, but this evening it started minimising to the taskbar when I clicked on anything. When I maximised it from the taskbar, it was in windowed mode. Changing it back to fullscreen just caused the same thing to happen again. So I restarted my pc and now kodi is starting fullscreen with a black screen. I can’t get at task manager to kill it off so I have to log off my windows account in order to kill it. When I login and run Kodi again, the same thing happens.

I have kodi setup using my GTX 750 ti with one hdmi out to run @ 60hz on my 4k tv, with a second hdmi out to my av receiver just for sound. This has worked perfectly to this evening.

How do I get a log so that someone here can maybe tell me whats going wrong?

System

Asus ROG Maximus VIII Gene
i7-6700K
24GB DDR4 ram
480GB SSD
Windows 10 Pro