Laptop Screen goes blank on boot

[MRR2]

I have a Gateway Model W340UA
AMD Athlon 64*2
NVIDIA GeForce Go 6100
Windows Vista Home Premium Entertainment... (32 bit)

First computer with Vista, have had it almost two years, used occasionally, didn't like the way the screen would go blank every time it had something to do. Was told it probably didn't have enough memory, upgraded to 2 gig, didn't make a difference. Lately, something weirder is going on.

Every time I start the computer, whether from shut down, sleep, or hibernate, it does everything necessary and I can watch the screens, until right when it gets to the point when I can start using it. Then the screen goes blank. Backlight appears still to be on, but it is as if the computer is sending a blank image in black to the screen. Doesn't matter what I do to the keyboard or mouse, nothing changes.

Here's what's really weird. If I plug in an external monitor, the screen comes back on with the image I would expect, my background and icons, then I can unplug the external monitor, and all is well until I shut down, sleep, or hibernate (or just leave the computer long enough for those things to happen with power savers... or if it shuts down because it overheats from running too long).

I've tried updating the NVIDIA driver, doesn't do it, says driver is up to date. Had it in for diagnostics, they (I believe) removed the driver and reinstalled it. Didn't help.

(If external monitor is already plugged in on boot, sometimes the picture comes up, and sometimes it doesn't.)

Any ideas?

On Edit, it doesn't make a difference if the monitor is powered on, just plugging something into the monitor jack seems to "wake up" the laptop screen.