black screen

I have an ADi PD959 19" monitor w/builtin USB hub. My computer(s)
is/are home-builds. There are four of them.

In my current situation, I have only the one monitor. One
monitor/keyboard/mouse to try to use on 4 computers. The monitor, kybd,
and mouse all work on each PC just fine.

So....I get a Belkin 4 port KVM switch. F1DS104U.

I hook up all 4 PCs to the KVM. I hook up the aforementioned monitor.
when i turn all the PCs on and then the monitor, the monitor doesn't
display anything. The screen is just black. If i disconnect the monitor
from the KVM, the monitor puts up a message saying "check video cable".
I plug the monitor back in and the message goes away and the screen is
once again black. If I disconnect the video cable from the currently
selected PC, the message comes up on the monitor. Hook it back up and
the message goes away. Black screen.

Let me say that this is a mystery and I know I can just go buy another
monitor. But this is a 19" CRT and it works great. I had my eye on a
Samsung 19" LCD, but it just doesn't even come close to the display of
my CRT.

Besides...I want to solve the mystery of the black screen.

Does anyone love mysteries as much as me and have any ideas????

I have a couple places to post results if I can get this solved.

BTW....Belkin is of absolutely NO help whatsoever. ADi has yet to
respond to my three day old email.

Cheers.....