Clip shows on PC but not on Mac

Hi all, hope someone can help…initially clip worked on Mac, then froze at welcome screen…finally got it to show on PC and erased which has rendered it usable on PC again…did firmware update - changed to MSC. So now while it will plug in and charge on my ibook does not mount as USB storage device. Many thanks to you all I can at least use clip on PC now. Would like to be able to use on Mac. Any ideas please???