Placing PDFs into quark is hit and miss, it relies on JAWS to interpret the PDF and turn it into a sort of internal postscript before output. If it works, chalk it up as you got lucky. InDesign doesn't have to turn the pdf into postscript it has access to the same PDF library that Acrobat uses. Your best bet for troublesome PDFs that really really really have to go into a quark document is to use Save As in Acrobat and select EPS then settings (that suit your Xerox). Then place this EPS into quark instead of the PDF. This was pretty much the first question I ever asked on this forum and this advice has been typed in many times by many people (well mainly by Erik :) )
... there was the puzzle of why the sun came out during the day, instead of at night when the light would come in useful.
Terry Pratchet