PowerBook external video problem

OK, so I just bought this PowerBook G4 1Ghz with a busted display for $75. Other than the busted LCD panel, it seems to work pretty nicely. I've already burned a few CD's, connected to my wireless network, even reinstalled Panther (just to get the previous owner's data off the machine). I'm actually using the machine to make this post.

I am having one issue, though, related to external video. Whenever I do anything that may put a strain of any kind on the video card, the screen blacks out and comes back when it's "safe", for lack of a better word.

For instance, if I take this Safari window and drag it wildly across the screen, it will cut out momentarily (sometimes for long periods of time). Other things like Exposé, Dock magnification, the Genie effect, even the cube effect that is used while setting up Mac OS X immediately after a fresh installation caused the screen to cut out.

So far I've (to the best of my knowledge) reset the PRAM and NVRAM, reinstalled the OS obviously, even removed the bottom casing and physically disconnected the computer's attached LCD.

While just using the machine for basic tasks, it looks great. The display is crisp and clear and completely uninterrupted. Should I just part this machine out or what?

What can I do? I'd like to buy a new panel and make this machine 100% again, but I'm afraid to put the money into it at this point.

I noticed this morning that when I first turned the machine on, I could do whatever I wanted and the machine behaved exactly as it should all the way through.

I also realized that I have not once seen or heard either fan inside the machine spin for even a second.

Could it be a heat issue? Maybe the GPU is overheating or temporarily disabling itself to avoid overheating?

pastrychef said:

Yes, it sounds heat related. I don't know what you can do correct it...

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Do you think I'd be better off just parting the machine out rather than buying a replacement display for it and avoid risking wasting my money?

Does anyone else have any thoughts on what I can do with this machine to get it working properly, or at least figure out exactly what is wrong with it?

pastrychef said:

I don't think it's an issue with your display, so don't buy a new display.

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Right, but the LCD panel is cracked. That's why I would like a new display.

pastrychef said:

If not... You mentioned that you didn't hear the fan come on. If you're good at such things, maybe you can open it up and see if it's clogged with dust or whatever.

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I had it apart to some extent, the fans are a little dusty. Think that could cause them both to stop spinning? I am worried maybe a portion of the motherboard is bad.