You don't mention which Adobe software he is using.
I have been using Acrobat ver 5.0, it has with it, a program called 'PDF Writer'. Once installed, it appears as a system printer. I simply plot to 'PDF Writer', & plot to 'Extents'. I get perfect .pdfs every time. - I have tried the Acrobat Distiller, but I have never been able to get it to work for me.
Hope this helps,
craigr