For some reason, Vegas has decided that whenever I want to render a loop (haven't tried not looping anything, though I imagine it wouldn't make a difference), the video comes out looking like this:

This looks TERRIBLE when the video is in motion. I cannot for the life of me figure out why this is happening. This actually happens quite a bit, but there doesn't seem to be any rhyme or reason to it.
My export settings are the same as I've always used, and those are the same as the settings spelled out in EADFAG. I've tried every possible combination of lossless codecs, frame rates, etc. and I STILL get that stupid ghosting effect. I've tried disabling motion blur on each of my video tracks. Nothing seems to work.
I've tried rendering that crap out and the attempting to fix it with AviSynth. That hasn't turned out so well.
I'm at a complete loss. The codec of the source clip doesn't make any difference - I've tried it uncompressed and with Lagarith, and I assume HuffYUV won't change anything either.
My project settings match up with my export settings, and both of those match up with my clip properties. I've tried changing everything just to see if maybe it'd make a difference, but to no avail.
Does ANYONE have any idea how this could be rectified?
For what it's worth, the clip in question was rendered out from AE, but it's not exclusive to this clip so I don't imagine that makes a difference either...