If I pulg the shuffle into my ibook it works flawlessly. if I plug it into my g5 imac - it shows up on desktop, opens itunes, shows up in itunes - then a window pops up asking if I want to update it (it already has the most recent update). If I click OK it atemps to update, but then has greyd out buttons. If I click cancel, it proceeds back to itunes and apears to load songs - but - there is no choice for auto update and the songs that are visible in the shuffle are greyed.
Both machines(ibook and imac) have latest and most recent software.