Concensus is to avoid the PM "export to PDF" feature. I use it frequently with little problem. Many have never been able to successfully use it. It seems to work well with smaller documents. To avoid problems, the best way to create a PDF is the 2-step process, which may seem like more work, but can actually be faster if you are distilling multiple documents.
Through the print dialogue, select a Postscript printer and the appropriate PPD. Best choice is usually Acrobat Distiller PPD. Under the Options tab, check the "Write postscript to file" option. You can select the folder using the browse button there. After hitting "Save" (which is normally the print button), you will be printing the document to disk.
Now open Acrobat Distiller. Set the "job options" according to the intended end use of document (screen, print, pre-press). Select Embed all fonts, deselect the subset option. Open document, then save it. This procedure, according to some of the gurus from the forum, produces smaller and better PDF files than using the "export" option. It is certainly the most stable, error free procedure.
Some recommended settings for PDFs: Default Resolution: for web use, 300DPI; For Press, 1200DPI; Compression, Color and Grayscale Bitmaps: for web use, 72DPI; For Press, 300DPI; Compression, Monochrome Bitmaps: for web use, 300DPI; For Press, 1200DPI; On all of the above, if it is for prepress, disable the automatic compression boxes. Enable Font Embedding for all fonts, disable Subset All Fonts.
For prepress, it is always a good idea to discuss the above settings with your printer, and to compose to a printer using a PPD for the printer they are using.