Green Pixels when playing video files

I have a Powerbook G4 15" Aluminum 1.5Ghz, had it for nearly 5 years now.

As of late when playing video files the screen does not display the video correctly, green patches start to appear in certain areas of the screen. This only happens when playing certain video files (wmv, .mpg), but for some reason when playing .avi or dvds the problem does not occur.

Does anybody know why this is happening? Is there any way i can fix this?

I've attached a screenshot showing the problem that occurs.



Any help on the matter would be great

Thanks

 

The image attached is from a dvd that I downloaded.

But this is also happening when playing small files video files in my safari browser?

Do you think it has something to do with the logic board?

 

i've checked the files on another machine, they work fine

So im pretty sure its my hardware.

Is there anyway to fix it?, if it is the hardware