DesignShop artwork is polyline. And, in general, should not have any splining.  If this occurs, there are several  possible steps you can take to avoid the problem.  

Step 1: Splined paths DXF file it could be due to version of the DXF file your CAM program is based on. To fix this problem, try exporting your splined DXF files from AutoCAD in a R14 or 2000 DXF format.  This will help to produce polyline DXF files that will work as suitable cut paths in most CNC software programs. 

Step 2:As a last resort, contact the software developer or their technical support team and providing them with a copy of the DXF file so that they can help with troubleshooting the problem you are encountering with their software.