Comment 24 for bug 1813663

I can confirm I'm having the same problem with a Dell Precision 5510 laptop. I have traced the problem to the startup item "/usr/lib/x86_64-linux-gnu/cinnamon-settings-daemon/csd-xrandr" it seems xrandr is freezing the system when it boots up connected to a Thunderbolt 3 Dock.

If I disable that startup item, I can boot up while docked just fine, I just can't change my monitoring configuration around. If I boot up using the 4.15.0-43-generic kernel, that startup option works just fine and everything works.

Somehow linux-image-4.15.0-44-generic has changed how the video card works with Dell laptops and Thunderbolt 3 docks; as soon as xrandr tries to fully initialize the graphics cards everything freezes up.