Run program

-If you press Win+Alt+O a new window with tabcontrol will open fine (or F11)

-Lock computer and unlock

-Press Win+Alt+O twice (one window will open file, second will be blank)

-Press Win+Alt+P (Or F12) to open window without TabControl (always opens fine)

If you remove line <ui:XamlControlsResources /> from app.xaml, it will always open fine