Deleting the widget_cfg.txt file from my config dir made it work again but then it stops working until I delete it again.
Edit: Nope this is not a fix, turns out when Glest closes it still has a process running and it wont run again until I task manager -> end process.
Edit: I've narrowed down what's wrong. When the game Crashes (isn't closed through it's menus or with alt+f4) it's process keeps running and the game wont start again until I manually end the process.