I've been using the Apple Video Adapter to display my iMac G5 on my tv. Recently, and unexpectedly, when I connect the adapter to my mini-VGA port, the display on the t.v. begins flashing and the screen will begin jumping very rapidly. I've plugged the adapter into other mini-VGA ports and it appears to be fine , and my T.V. displays all other external components fine (dvd players, game systems etc.) which leaves the mini-VGA port itself as the problem. Any suggestions on how to fix this?