I find myself having to do some surgery on my main desktop computer, so
I decided to connect my laptop to my main computer's monitor, keyboard,
mouse, speakers, etc... etc... The monitor works for the computer
manufacturer's start screen, Grub and Ubuntu start up. The problem is
that when it gets to the sign in screen, the computer no longer sees the
monitor. All I get at that point on the monitor is "No input device
found". Any ideas on how to cure this so that I can use an external
monitor?

On the bright side, while trying to get an external monitor to work on
this laptop, I accidentally discovered how to install my wireless driver.