Graphics Card Hardware does not always support the drawing model that PolyCAD uses. To check this:
1. Create a polyline (Create -> Polyline)
2. In the graphics window, Click and drag to draw.
If the "Rubber Banding" is smudged across the screen as shown above:
3. In PolyCAD Options in the Attributes panel, to System Options.
4. Change the "Resolve NVIDIA Double Buffering Problem" box.