Use the DWG to PDF option instead of Export to PDF.
Alternately, try the Autodesk fixes. (HyDraw CAD does not control the print options.)
Random-rays-and-lines-show-up-in-PDF-printed-from-AutoCAD.html
Unwanted-lines-show-up-on-plotted-output-from-AutoCAD.html
Extra-drawing-lines-show-up-in-PDF-plotted-to-Adobe-PDF-from-AutoCAD.html