The Spelling and Grammar check tries to be helpful by ignoring words in subsequent sessions. If that's not what you want, reset the feature to start fresh.
- Execute the Spelling and Grammar feature as you normally would—press [F7] or choose Spelling and Grammar from the Tools menu. Check the Review tab in 2007 applications.
- Click the Options button.
- In the Proofing Tools section, click the Recheck Document button.
- Click Yes to confirm your choice.
- Click OK to return to the spell check task.