I would guess that it's the atmosphere, tho I don't have a current Vue anymore[demo over boo] I have had similar experiences both in Imagine 3D when using Volumetrics, which is how Imagine produces atmospherics, and way back in bryce and terragen. The answer to the 'crawlies' you're seeing can, to some degree be solved by rendering single frames and re assembling in AE as you suggested, but by and large, computers , I feel , just can't cope with all the miniscule calculations in terms of pixels. Someone post an example to prove me wrong....please...but no matter what software I've tried, the crawlies are omnipresent...been thinking, for a project I'm working on now, of , after rendering frames, printing them out and shooting to actual film as then you can have all the subtlties without concern for the number of pixels on my display.. But that sure don'r solve your problem so...someone/anyone...please post an answer as I'm fairly certain the answer can be implemented in any program once I know what the solution is.

 

Once in a while I look around,
I see a sound
and try to write it down
Sometimes they come out very soft
Tinkling light sound
The Sun comes up again