The style for those paragraphs/words probably has the Do Not Check Spelling
attribute turned on.
In 2003 and prior:
1. Select all (Ctrl+A to select the whole document).
2. Double click on the language button at the bottom of the Word window (or
Tools, Language, Set Language).
3. Select the Language required in top section of the dialog box.
4. Clear the "Do Not Check Spelling or Grammar" check box. While here also
clear the "Detect language automatically" if this is checked. If either is
gray, then that means that part of the selected text has that setting, and
part does not. You want that box to be white, not gray or checked.
5. OK.
The document should now be open to spelling and grammar checking.
Now click the Spelling & Grammar button or press F7 to run a check. You
might need to go to Tools, Options, Spelling and Grammar and click the
Recheck Document button.
In Word 2007, Review tab, Proofing group, Set Language, make sure that the
required language is selected and that the two check boxes at the bottom are
UNCHECKED: then press Default.
Now click the Spelling & Grammar button or press F7 to run a check. You
might need to go to Office button > Word Options > Proofing and click the
Recheck Document button.
Close Word and make sure to answer YES to save changes to the global template.
Spell check is a formatting attribute of the text. If you copy formatted
text from another document then the formatting will come with it and if that
include the no proofing option, then that's what you get. You need to either
re-apply the proofing parameter (as described above) or use Paste Special
Unformatted Text so that the formatting of the destination is adopted.
Also see
http://sbarnhill.mvps.org/WordFAQs/MasterSpellCheck.htm.
If when you say "new word document" this means that all new documents
created have the "do not check" setting applied, you will need to do the
above to the necessary normal.dot template (or .dotx/m for 2007).
Hope this helps
DeanH