|Some things you can look at to diagnose the problem:|
Does the screen always go dark at the same point during boot-up,
or does it vary?
Does it ever come back on by itself if you wait a few minutes?
If you start the computer with the monitor turned off, what happens
when you turn it on after the operating system is running?
Connect a different monitor to the computer, and/or a different
computer to the monitor, to see which has the problem. This isn't
a sure thing. The video signal from the computer might too weak
for one monitor but strong enough for another.
-- Jeff, in Minneapolis