If you have a pic/screen shot of what you're attempting to cut along with the settings used for your toolpaths, that would be helpful. One possibility could be your finish tool stepover % is too high. Vertical walls can cause what you describe. Using a dished design will help. While it can't be done in VCP, adding a slight draft to the model will help greatly for vertical walls, as the tool will ramp up and over instead of stopping and lifting, but this has to be done in Aspire etc.
Scott
"It’s easier to fool everyone than it is to convince them they've been fooled" - Mark Twain