What is also possible is that the files actually *are* changing. If this is a multi-user environment, it is possible the files are being changed. They may even *look* the same, but *aren't*. You said yourself you are indexing multiple machines, multiple documents. I have had a similar situation with pdf documents. I had two copies of the same document, same filename, I opened them and had the same content. These files were hard copy papers scanned in via an Ikon scanner, turned into pdf documents. It turns out.. Somebody made a mistake! And scanned the same document twice! And named it the same! md5sum was telling me these were different documents, and I was refusing to believe it beacuse my eyes told me different. Watch out for this possibility.