What causes blending? (picture included)

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When I render my video in Vegas.. I get this happening.

http://img230.imageshack.us/img230/191/snapshot200512180103039cp.jpg

I have deinterlaced my footage, and there isn't any blending like this even if I go frame by frame in the AVSEdit preview to see if any of this is going on just incase I may have deinterlaced it incorrectly and I don't see any of it.

Even in my timeline in Vegas, if I go frame by frame I get no blending, but then when I render it I get it, even at times when the input and output is the same framerate. So what causes it and how can I prevent it from happening? Thanks.

I've worked on this for a while and already had a lot of help in another thread (http://www.animemusicvideos.org/phpBB/viewtopic.php?t=61437) (not a doom9 thread), but this problem is still continuing and would like some help from here.

Edit: OK it has come to my attention that akira is progressive and that I'm suppose to use force film right? I was sure I did that but as I'm testing right now, I don't see any blending. I think I did honor pulldown frames and that could of been causing the problem. If the problem persists, I'll report back.

Edit again: I've tried force film, made it at 24fps in my avs script and made it 24fps in my Vegas project and 24fps on my export yet still getting blending. :(

Here's another screenshot of what I get when I render.

http://img466.imageshack.us/img466/7968/snapshot200512200203191mw.jpg

and a clip.

http://stormmetropolis.com/test/Organ%20Donor.avi

Here it is when I render it in Vdub.. looks fine

http://stormmetropolis.com/test/Akira.avi

Please help.

Update: Look at the other thread. Looks like me slowing down the footage a tiny bit caused the blending.