Take one of the PDFs you see these thin lines in, load it into Acrobat. Zoom in increasingly where one of those lines appear. Does the line get any wider? Likely not. So it is a screen artifact called stitching. Rarely does this stitching even print to low-end printers. I have never had stitching affect my own printing, much less a print job using commercial printing equipment.
Take care, Mike
No, it is not a screen artifact. It carries on through to the PDF file I publish as my magazine.
The workflow is 3D CAD to PDF, place the PDF in InDesign document then Exporting the document to the final PDF.
The lines are visible in InDesign, sometimes in the resulting Exported PDF and if one prints the PDF page the lines show up randomly on a laser printer.
Lines do get wider.
This would kill even a commercial print job.
The new CC software series has cured the problem, whatever it was.
I've switched to Windows 7 Pro, 64 bit.
Thanks for your help.