My LCD monitor shows a black screen after changing screen resolutions!

I don't know why but my LCD monitor shows a black screen after each change of screen resolution.
But when I manually change the resolution through the Display Settings, it worked fine.

For example, I tried using the slide show feature of Windows Photo Gallery in Windows Vista. When switching to slide show mode, it always change the resolution to 640x480. But after it changed to 640x480 screen resolution, the screen turned all black with the LCD monitor still switched on! The only way to return it to normal is by turning off the monitor, wait a couple of minutes and switch it on again. When I tried to turn it off and turn it on again, without waiting for few minutes, the screen went black, then I tried to turn it off and on again, but the same thing happened, the screen went black. So I just waited for few minutes then turned it on again, and it returned to normal.

Another scenario is while I'm playing games, like Soldier Front.
After each game, the game switches from it's full screen resolution (1024x768) to my native resolution (1400x900), which is normal. But when it change to 1024x768, 1400x900 or any other resolution I configured, the screen went all black. So I have to do the same procedure; turn it off, wait for few minutes, then turn it on again.

What's the problem? Is it my NVIDIA GeForce 8400 GS video card or my HP w1907 LCD monitor?