The prompt is most likely due to the fact that the document was originally opened in one format and is being saved in another but you're not releasing the version in its original format. I would expect Word to behave this way in all versions. All you need do is change:
WW.ActiveDocument.Close
to:
WW.ActiveDocument.Close False

PS: I also note that, although you have:
FileName = "C:\tmp\test.doc
you don't use it in:
WW.activedocument.SaveAs FileFormat:=SaveFormat

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]