There are numerous possibilities:
1. A corrupt document, especially if only the one document is affected.
2. A rogue 3rd-party addin.
3. A faulty Office installation.
4. A faulty printer driver.

1. 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.

2. If running Word in safe mode (i.e. hold down the Crtl key while starting Word) resolves the problem, a rogue third-party addin is the most likely cause. In that case, re-start Word, disable all third-party addins, then progressively re-enable them until the culprit can be identified by its problematic behaviour. Uninstall (and, perhaps, reinstall a compatible version of) the addin.

3. To ensure Office is working properly, try repairing the Office installation (via Windows Control Panel > Programs > Programs & Features > Microsoft Office (version) > Change > Repair).

4. Check your printer maker's website for an updated driver. Uninstall the existing driver then reinstall it or the updated driver, as appropriate.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]