We recently switched to an i Mac. The Best Buy Geek Squad did the data transfer from our PC and Thunderbird didn't seem to transfer, so we downloaded Thunderbird again and it seems to work fine. But now when we are prompted to upgrade to the latest Thunderbird version(24.4.0), the download does not work. We have attempted this multiple times with no success. BB suggested uninstalling Thunderbird and reintstalling it. Is this the right course of action? Thanks!