artifacts in dvd-slideshow movie

[DawgG]

i have created several movies from jpgs with the latest dvd-slideshow-release (on different systems) and they all show some artifacts which weren't in the original pictures. dvd-slideshow ran fine, no errors.
the artifacts are brilliantly, mostly white-colored dots/lines of dots that run along (some parts of) the seams of different colors, eg at the border of a face in front of a dark background, but not the whole way and not everywhere or in every picture. (a bit like selecting sth. with the "magic" selection tool in gimp).
as said, the artifacts are not there in the original pics and i have used "original" pics (directly from camera) and converted pics (converted with "convert" either only in size/orientation (--auto-orient) or in file-format (game-screenshots from .tga to .jpg).
i have re-emerged mjpegtools and imagemagick (and transcode on one system), but the artifacts still occur.

how can i fix this problem? any ideas? (i might contact dvd-slideshow's author but wanted to ask here first.)
thx four your help!
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DUMM KLICKT GUT.