> Interestingly, when I run "Try Ubuntu" from the bootable USB device, I can connect the monitor and have Ubuntu working on both screens. It seems that, somehow

> Interestingly, when I run "Try Ubuntu" from the bootable USB device, I can connect the monitor and have Ubuntu working on both screens. It seems that, somehow, the problem is with the installed OS, rather than the OS itself. Frustrating. But this part seems like a hint that figuring out the issue won't take too much longer with some investigation.