When I view HD programming, I get what appears to be a scan line running horizontally through the picture. It scrolls from bottom to top about every 20 - 30 seconds. Its thin and just looks like a ripple.

This doesn't happen in non-HD programming though.

My setup is like this:

I have a Comcast/Motorola DCT3412 Dual Tuner DVR / HDTV Capable box connected to my Dell 2407WFP via component cables.

The monitor has a resolution of 1920x1200.
On the cable box, TV Type is set to 16:9, YPbPr Output: 1080I, 4:3 override 480i.

The monitor was replaced on RMA a while back and this happened on both displays. The component cables are well shielded, if not a bit too long for their application. The display is on top of the cable box; connections are less than a foot apart, but the shortest cables the store had were 6 foot. They aren't coiled up or anything. just sagging behind the desk.

Any thoughts would be appreciated.
I've tried recording the anomaly but I can't seem to capture it on my cell phone.

Thanks!

Sounds like some incompatiblity with the refresh rate, which typically shouldn't happen with LCDs, right????

Or, it may be an incompatibilty with 1080i. Can you set the cable box to 720p and will the Dell monitor accept 720p?

ft