Hi - i have been switching macs lately (macbook, 15" macbook pro, air.. trying to find the best one for me ;-) and when i tried to activate parallels on my latest mac, it said i had exceeded the # of macs activated on. The thing is, i clean the hard drive on my old mac before i return (or sell) so i never have more than one instance of parallels installed. What do I do? I have parallels installed on the macbook pro i own now and I cant register for the reason above...