I installed ubuntu from a live USB as dual boot alongside windows on a Razer Blade laptop. During installation an external monitor was plugged in the laptop. Now, the external monitor needs to be plugged in on Ubuntu start, otherwise Ubuntu crashes right after I enter my login password. Once Ubuntu is started I can use it normally, but if I click on the icon for system settings, it crashes. Also I can't turn off the computer from the top right menu, I can only turn it off by pressing on the power button for twenty seconds. What should I do?