It's possible the document has acquired some of corruption. Corrupt documents can often be 'repaired' by inserting a new, empty, paragraph at the very end, copying everything except that new paragraph to a new document based on the same template (headers & footers may need to be copied separately), closing the old document and saving the new one over it.
Other than that, there may be some other problem with your system. Faulty printer & display drivers are possible culprits; you might try updating both with the latest drivers from the makers' websites.