Could be either a problem with the display itself or a problem with the graphics module in the PPC. Try a different display and see if the problem still exists...that will tell which is at fault.
I got a moment and disconnected the HD Cinema display from the PPC. I powered it on just to see how the LCD display of the laptop would be. Sadly enough, it also has these same odd cross lines in the same areas as when using the Cinema display. So as you suggested, this narrowed things down. And it must be a problem with the graphics module as you suspected on the PPC itself. I am assuming this is a more complex problem? Something worth repairing?
Anyway, on another note, my husband is WAY overdue to UPGRADE to another laptop. I have been telling him this for some time. He is just attached to his "baby"! Mostly, he wanted to KEEP using the HD CINEMA DISPLAY. SO this is now an option even if he buys a new Macbook. I think we would need an adaptor for it.
Just for your interests sake, this older HD CINEMA DISPLAY has a matte surface and delivers a wonderful viewing experience. As opposed to my glossy iMac display which cause me eye strain and headaches way too often!
Thanks again for your valuable input.
You are welcome, and glad to be able to help.
There were users disappointed when the new iMacs came out with no option for a matte finish display...I have the glossy display on my iMac and MacBook Pro and keep moving around to reduce glare, can be very annoying.
A PPC is really dated even though they are good running and solld machines. Repair of a graphics module would be more expensive than the computer is worth...but like a car, if it is paid for and you really need it, can be a difficult decision.
If you and your husband start looking at the new models, MacBook Pros not cars, keep in mind that the 15" standard MBP has a matte hi-res screen option. The Retina does not. And, the regular MBP can be user upgraded in memory at a later time if you want to do so. The Retina, like the Air, cannot be upgraded at all. All components except the battery are soldered to the logic board so what you buy is what you stay with. Same with the new iMac 21", no upgrade by the user. The 27" iMac can have the ram upgraded by the user but that is all.
Just some things to think about.
It has been a pleasure helping, good luck making decisions on where to go with your computing.