It would also be helpful to take a peek at the "known good" vim-edited file (in SlickEdit), and show Hex view, just to make sure something strange isn't going on with the file encoding. Switch back to normal text view, do some edits in SlickEdit, save the file, and then re-examine the hex display.
If you're seeing strange sequences show up, then this could be a case of file encoding confusion. The easiest way to clean that up is to open the file again (in SE) and explicitly select the proper encoding. Once you've selected an explicit encoding, SE will remember what you've chosen and use that every time that specific file is opened.