Program is Sony Vegas 8.
I was recently forced to upgrade to Windows 10 and had all my preferences reset, and since then I haven't been able to render in lossless avi wtihout really bad interlacing. At first I thought it was the footage, but it's happening with ALL footage, including clips I'd cut and prepared before the upgrade. I've tried comparing settings on my laptop and desktop (where I'm having the problem) but I haven't found any differences other than the version of AMVpack installed.
Filtering after the render has varied success, but that's side-stepping the issue in the first place.
Interlacing (looks more like ghosting on some displays, but disable resample is enabled and framerates match so I don't think that's it):