Office 2007 Word Spell Checker Does Not Work

I have an academic version of Office 2007 installed on Vista Ultimate 64 bit. MS Word’s Spell Checker does not work. I have checked that the Style does not defeat the spell checker, that the language is US English, that the AutoCorrect settings should enable checking as typed, I have no custom dictionaries installed or enabled, etc. Googling has got me nowhere, searching in TechRepublic (a quick attempt) came up empty.

Any and all suggestions are greatly appreciated.

Thanks,
Marshall