Strange problem DivX-encoding letterboxed video

[Swan]

Hi all,

I'm having a weird problem I just can solve.
I'm encoding music videos I have captured as Mpeg-2 (720 x 576 PAL) to DivX 3 and whenever the video is "letterboxed", the problem occurs.
On clips that are full 4:3, I can crop the black and the junk off the sides, and the clip looks terrific after encoding.

The problem I have is that in the area on letterboxed videos where the black border sort of "meet" the film content, the black pixels at the border "come alive" and look like marching ants.
It's hard to explain what it looks like, but I have uploaded a short clip to demonstrate the problem here:
http://w1.837.telia.com/~u83704167/clip/cut.avi

My script looks like this:

LoadPlugin("mpeg2dec.dll")
LoadPlugin("decomb.dll")
mpeg2source("eur.d2v")
Telecide()
crop(10,44,700,489)
BicubicResize(576,368,0,0.5)

I am using Decomb 4.0, Avisynth 2.0.6 (downloaded from Sourceforge) and and Dividee's Mpeg2dec.dll (downloaded from Doom9. File date 2001.08.16).

I see the "marching ants" even when commenting out Crop and Resize and viewing the .avs in MediaPlayer 6.4. When I comment out Telecide (), "the ants" disappear.

/Swan