monitor won't resume

I have Windows XP Pro SP2.

If the system has been in standby for only a few minutes (I don't know
exactly or even approximately, how few minutes), the monitor will resume
(come on) along with the rest of the system. However, after having been in
standby a sufficiently long time, everything resumes except the monitor
screen. Only the little green light on the monitor comes on. Then after a
minute or so, the light becomes amber and then eventually it turns off
altogether. If I hit the power button soon after the light goes off, the
screen lights up. If I wait too long to hit the button, then only the green
light goes on, eventually becomes amber and then eventually turns off.
Again, if I hit the button soon enough the screen lights up. If I hit the
button at any other time, there is no effect.

I have since updated the graphics card driver (The card is an NVIIDIA
GeForce4 MX420.) and have tried setting the hardware acceleration down.
Neither measure solves this problem.

This problem occurred at the same time I started having mouse problems.
Turned out the mouse was no good. Replaced it with a Logitech wireless
optical mouse. Works great but I still have the monitor problem.
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ray124c41