When you hit the print button in the PDF Reader software, it will try to print to whichever printer is set up as default WITHIN THE READER SOFTWARE. This will not always be the same as the printer that, for example, Word picks up from Windows. As an example, if you had two physical printers attached to your computer (say, an HP and a Cannon), the Windows default may be HP, but with the Reader software, the Cannon may be set. That's OK if you have two physical printers like that and they are both switched on and working, as it will just come out somewhere different to where you expect. But if you have some form of PDF Writer software installed (Adobe/CutePDF/etc), this will behave like another printer. So it could be that, the Writer software is set as the default printer with the Reader software. What will then happen is that you think a paper copy will be coming out, when in fact, an electronic copy will be created somewhere.
Thinking this out while typing that, another posiblity is that (in the same manner), the Reader software may be set to print to a printer that is no longer working/attached to your PC. This will usually throw an error message, but not always!.
Either way, instead of printing by hitting the printer icon, try drinting via the File/Print option on the menus (exact wording will depend on which Reader software/version you have). This should give the option of changing which printer to "print" to, so you can confirm it is correct.
