Well I first saw this problem (not me, another user) some 6 months ago and disabling divxg400 fixed it.
I experienced it 2 days ago
I've been through thorough testing on the crop system of a specific encoder and 2 of the 15 videos I got were distorted like that.
disabling divxg400 fixed that. presumably there is a specific setting in divxg400 to change but I don't want to waste time on a device I don't use ;)
oh, I just checked something and it appears that both my distorted videos have dimensions non divisible by 16 (they're 718*286 and 716*286) [the other test videos have standard sizes - multiples of 16)
(I'm still on build 490
)