I had the same issue.
My Sony FX1 shoots in 1080i Not progressive, so I was leary about setting my project to progressive. I left it 1080-60i (1440 x 1080)
HDV. UpperField.
I had the “Stair Stepping” and “Streaking” look no matter what I rendered at. I wanted the best quality for DVD regardless if I had to wait 24 hours for a 1hr real-time render.
What I did was render to the best .wmv 8bit using project size & best.
But the magic key was bringing up my Super Sampling to “2” on the video bus channel or better yet “3” if you have the render time to spare.
This also takes care of the “Twinkling” effect you get when you put high-res still photos on your timeline that may not be even close to your project or render settings.
Not sure if this is the orthodox solution, but it seemed to work for me.
Rick W.