I was not able to reproduce your problem, but I think this may occur if on the computer has been installed 97 (8.0) version of Word, which has been deleted (not uninstalled) but a new version of Word is installed after that and the registry can point to some file that is not existing.
Try the following code:

oWordApp = createobject ( "word.application" )
nWordVersion = oWordApp.Version && You can check this if you need to ensure that Word is version 8 or above.

Hope this helps