Is it Oulook or Outlook Express? The 2 are very different programs and we need to clarify which one you use.
This question has been asked several times in the past, and research shows it only affects Outlook Express. We've helped people who say they have issues with Outlook when they are actually using Outlook Express.
If you are using Outlook Express:
The issue you describe crops up in Outlook Express after installing Office 2007.
Since Outlook Express does not have a spell checker, it relies on spell check installed by MS Office
Programs. If you had a previous version of Office and upgraded, the new 2007 files are incompatible with
Outlook Express. Microsoft is aware of the issue but has no plans to correct it.
If you want to use spell check with Outlook Ecpress, you will have to
1) uninstall Office 2007 and go back to a previous version
2) install a third-party spell check for use with Outlook Express. This is the better option, especially if you purchased Office 2007. You don't want to uninstall it and end up wasting your money after paying for it.
Microsoft article about the issue:http://support.microsoft.com/kb/932974
Also read this Outlook Express Spell Check is French after Office 2007 install