Interference from S-video connection
 

Here's the thing . . . I have component connections going from my DVD player to my Sony Wega TV. I also have an S-video connection coming from a notebook PC. When I watch DVDs and the PC happens to be on, I get a faint white vertical bar that moves across the screen repeatedly. So naturally I turn the PC off and it goes away. But is there a reason that this is happening? Do I have an inferior S-video connector (or component connector)? Any thoughts?

Sounds to me like rf interference from the pc itself. Same reason why you turn them off on planes at certain times.

Try the pc in the same spot without the svideo connected and see what happens.