Turn off auto-hyphenation or suppress it for the one word in question.
Tools|Language|Hyphenation... uncheck automatically hyphenate or
Tools|Language|Set language...|Do not check spelling and grammar for the
selected word.
This usually indicates that either the font or the document is corrupt. If
the font has become flagged as a "symbol" font, Word will treat it like
Symbol or Wingdings (which can be broken anywhere). But a corrupt document
is more likely; see http://word.mvps.org/FAQs/AppErrors/CorruptDoc.htm