Not sure exactly what is causing the problem, but two things to try:
1. Select a different default printer in Windows. Does the problem
persist? If the problem goes away, then it is caused by the printer driver
for your normal printer. Try deleting and reinstalling the printer in Start
| Control Panel | Printers.
2. Work through the troubleshooting steps listed in
http://word.mvps.org/FAQs/AppErrors/ProbsOpeningWord.htm .