I submitted this to Apple. 1. Put a document on a USB flash drive. 2. Open it (Preview, Pages, it doesn't matter as long as its an app that supports Autosave). 3. Make a small edit. 4. Close the document with Command-W * 5. Note that there is no warning given about the file being changed and saved. 6. Re-open the document. 7. You can't use versions to get back to the original file. Conclusions -- Lion's protective "autosave" can cause accidental loss of data because it pretends to run on media that doesn't support it! * Command-Q works as well here, for those that can't get in the habit of using Command-W to close a document.