Monitor trouble?

Over the past 2 months, a fault seems to have developed with my
monitor which is a Mitsubishi Diamond Pro 720, nearly 10 years old,
but still a very good picture. The graphics card is 32 MB NVidia
GEForce2 MK.

Whenever the computer goes into hibernation or standby mode, and I
power off the monitor, then come back later and switch it back on, the
standby light is blinking, instead of being a constant amber. Any
attempt to bring the monitor back to life (moving mouse or hitting
keyboard) will not shift the monitor out of its blinking standby
state. If I switch off the monitor disconnect the power and disconnect
it from my PC, then just reconnect the power and switch the monitor on
again it is still is in the blinking state. What should happen is a
constant standby light.

The only success I have had in restoring the monitor back to normal is
to disconnect the graphics card cable at the monitor end then power up
my PC and immediately push the cable back in while the monitor light
stays green. This sometimes works but not always. If it works then the
monitor stays an and all is fine. But sometimes, even when the monitor
does switch on normally, it will behave for a couple of minutes, then
the picture will fade and the blinking standby mode is resumed. When
that happens, switching the monitor power button off for a few
minutes, then on can solve the problem, but more often than not it
doesn't.

I suppose the obvious solution is never switch off the monitor power
button while the PC is in standby/hibernation, but as explained even
if I do that when constant standby light is on, when the monitor wakes
up it can often resort to the blinking standby state 2 minutes later.

My main suspect is the cable or even the monitor itself. After all why
does it stay in the blinking state when disconnected from the PC and
its power switched off then on again. I don't think it's anything to
do with the video card, which is shown to be working fine in Device
Manager. On the other hand possibly the video card may be tripping the
monitor into its blinking standby state. But then why doesn't it do
this all the time. Eg.not happening at the moment.

Any ideas?