It might be a normal.dot or registry issue. I'd take a look at the steps
described in this article, and see if the steps shown provide relief. Note,
even though the title deals with problems starting Word, the same issues can
cause problems such as you're seeing.
http://word.mvps.org/FAQs/AppErrors/ProbsOpeningWord.htm
By the way... what version of Word is this, and do you have the problem in
other MS Office applications?