Sometimes in Microsoft Word or Outlook the default template file normal.dot can become corrupt.
To restore it do the following:
1. Close all office applications including Word and Outlook.
2. Download normal.dot from here.
3. Save it to your desktop and rename it from normal.doc to normal.dot.
4. Copy it to
C:\Documents and Settings\<youraccount>\Application Data\Microsoft\Templates
5. Replace the file that is already in that folder.
When you then open Word or go to create a new message in Outlook 2003 the problem should be fixed.