Well, the OS # I have for 7.5 is 7720. I thought it was supposed to be 7430 [that I had for a short while during the download kerfluffle it put me through. I can understand the normal problem with Windows what with so many hardware versions, but with the number of phones running WP7 and 7.5, it makes little sense. Even after all of the above confusion [and I have been using computers since 1960] not 1970, 1980, 1990, & 2000 or so, it still doesn't work just right. They have been letting the programmers write the documentation again!!!!!