Either has not safe Z set or the code is setting Z to cutting depth before moving. Common problem with some g-code programs. With BobCAD you have to taylor the post processor or it will skim over at Z0 to the first cutting location which is not good practice. Check your code as that will tell you the moves and will also tell you that units it thinks it is working in. From there it should be pretty straight forward on finding where the error is. Fixing it will be finding where that control for z is in the ArtCAM set up.

Michael