CompuServe Messages

I've hooked up a PAR and a Micropolis HD. When playing back the ani files there is a disconcerting black bar that seems to slowly roll or crawl through the animation; it alternates with a lighter bar. I've changed cables, and monitors. I'm outputting to both VHS and SVHS, viewing the animations on both a Sony GVM 1311Q, and a Sony PVM 1341. These test animations were rendered to frames, Q Factor 23, Block Limit 200. Any body got any ideas?? Many Thanks–Carlton