corrupt files in Word 2000

I get this error message, “This document may be corrupt. To preserve the contents: Choose Select All from the Edit menu, then choose Copy from the Edit menu”, everytime I open a document in word 2000. I went on line to search Microsoft’s Web site and they said to go into the Regedit “Hkey_current_user\software\microsoft\office\9.0\word\options – but it’s not there, please help…