VisualMill Generating Extra G-code/Cuts???

I've made two simple models in Rhino and imported both into Demo version of Visual Mill and the Free version both with the same results. It is cutting extra depth on the Z-axis. I have a 1inch thick model with .25 cutout throughout and when it generates the toolpath it cuts extra ~.75 in certain spots. The first was just a simple rectangular cutout and it cut through, then I created this one and it cut some of it fine then the rest when complete z-depth. Here is a simple video of the toolpath simulation in visual mill and you can see the obvious extra cut www.fusionxstudio.com/movie/cnc2.avi Should I use a different program to produce the g-code, am I using the wrong processor-"general" I've posted that question earlier and in the visual mill group but I'm the only post in a few days in that group. Any help would be appreciated. I've finally finished my first machine and I'm ready to start playing.

Thanks,

Barclay

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