AutoCorrect

• Microsoft Word's AutoCorrect feature maintains a list of common misspellings and mispunctuations of words, and is designed to automatically replace these misspellings with the correctly spelled words, should you type any of them. If AutoCorrect has become confused and is capitalizing letters it shouldn't, you can modify its settings using Word's interface.
  
  

Accessing the AutoCorrect Settings

• Click the Office button in the top left, then "Word Options," then "Proofing," then "AutoCorrect Options." In earlier versions of Word that do not have an Office button, open the "Tools" menu instead and click "AutoCorrect Options." A panel of settings will appear, all of them concerning various small corrections the AutoCorrect utility can make to your typing.
  
  

Automatic Capitalization

• Among the AutoCorrect settings are "Capitalize first letter of sentences" and "Capitalize first letter of table cells," either one of which might be causing your problem with rogue capitals. If it's the first word of a sentence or a table cell that's being inappropriately capitalized, uncheck the relevant box to deactivate the setting, then click "OK."
  
  

Adding Exceptions

• Ensure that the word you're having trouble with won't be corrected anymore by clicking "Exceptions" and entering the word into the "Don't correct" box. If you don't see this box after clicking "Exceptions," try selecting the "Other Corrections" tab. Click "Add" after you've typed the word, then click "OK." AutoCorrect should ignore the word from now on.