It appears FastPictureViewer fails to add the extension to the file name when generating XMP files for image files using a dot [.] or dots in the name. For example, for a file named "5DII_2009.12.18_4154.CR2", the resulting XMP file created is "5DII_2009.12.18_4154". The extension XMP is left off, rendering it useless.
Bob