NTSC Input Jumpy

[Fuego]

I have a Matrox Marvel G200 running under NT using the beta 2 video Tools. Any NTSC input from either video or DVD jumps up & down vertically by a couple of millimetres or so. This doesn't occur under win 98. Any ideas why or will I have to wait until new video tools are released to correct this.

BTW. PAL input is ok
Thanks.