Problem:

Spell check does not work in Office 2010.  Intellisense does not detect incorrectly spelled words and manually running spell check does not work either.

Solution:

  1. Click on Office Button | Word Options | Add-Ins | Manage: Disabled Items. If you see any disabled items that relate to spelling, try enabling them.
  2. If the previous suggestion doesn’t help, then:
    a. Close Word and any other open applications.
    b. Click on Start | Run | Open and type “regedit” (without the quotation marks).
    c. If the following key exists, delete it.
    HKEY_CURRENT_USER\Software\Microsoft\Shared Tools\Proofing Tools\1.0\Overrided.
    d. Exit the Registry Editor.
    e. Restart your computer.

NOTE TO SUPPORT STAFF:  The Windows 7 registry editor will prompt for an administrator password.  It will show the HKEY_CURRENT_USER tree for the user credentials provided.  Have the non-admin provide his or her credentials or you will not see the correct tree.

Pasted from <http://answers.microsoft.com/en-us/office/forum/office_2010-word/office-2010-spellcheck-is-not-working/df78d1af-1d42-4c7f-aed3-571997e6323d>