The OSD and the source are both scrolling perfectly in synch and the OSD is positioned correctly.

I also changed the video input from "Auto" to "Composite" for both and it didn't affect things. Unremarkably if I switched to an unused input type (i.e. S-Video or Component) the OSD snapped back into place properly.

I called earlier and spoke to Steve. He informed me that apparently they've had problems before with particular video games causing problems with the video transcoding. After discussing the issue he suggested that I isolate the devices causing the problem from the signal path and check again. Apparently someone else had a problem with their video due to a bad ground on their satellite receiver coming through into their signal path. After removing everything else feeding a signal in I tried again and there was no change.

Steve also suggested that I try feeding in a different source on the same composite inputs that are causing the problem. I'll probably eventually run a good dozen or so DVDs through it, but honestly I doubt whether I'll be able to recreate it. Out of about 20 some-odd Gamecube titles only this small part of one game has ever caused any issue. Likewise the input itself seems to be unrelated since it has occured with two different sources on two completely different inputs.

It also bears mentioning that aside from the vertical hold the video is transcoding correctly. I stil get a good picture with proper color and everything. It just won't stay still!