Installed a new Sony 42 inch PFM42B2 plasma screen this past weekend. It came with ferrite cores for both the AC cord and the video cables. I have a slight flickering appearing on screen when I am displaying the computer on the plasma screen. I have tried different refresh rates and resolutions. I do not have the flickering problem when using any other source. How do ferrite cores work - would they help with the flickering? Any information or help would be appreciated.