The fields may be getting messed up when Vegas tries to rescale the footage.

You could use VirtualDub and a couple of its built-in filters to convert it to 720x576. First of all, apply the "deinterlace" filter and set it to "unfold fields side-by-side" Next in the filter chain, apply the "Resize" filter and resize it to 1440x576 using the "Precise Bicubic" filter mode. Last filter in the chain is the "Deinterlace" filter again, this time using "fold side-by-side fields together." If you don't have a VFW compatible DV codec installed (like the one from MainConcept) then you will have to save the file using another codec, the Morgan codec may work here. Although, if you want to avoid another MJPEG pass, then the free Huffyuv v2.1.1 codec is lossless or, if the footage isn't that long, save it uncompressed. Any way you do it, you can then use use Vegas to convert it to DV. If the field order still isn't correct, you can right-click on the clip in Vegas and change its field order by going to "Properties" > "Media" > "Field Order"

Virtual Dub web site

Huffyuv v2.1.1 download site

Note, there is a Huffyuv v2.2.0, but I have had issues with it in WinXP. Also, VirtualDub has a built-in MJPEG decompressor, so you could use its MJPEG routines instead of the Morgan codec. When you open the file in VirtualDub, check the box that says "ask for extended options after this dialog" and select "Use VirtualDub routines for MJPEG.")

John