I have a very old purple iMac, circa 2000, with an old version of iMovie. I copied the files onto a USB and tried to open/import them onto my new Intel Core 2 Duo, 3.06 GHz iMac. However my new iMac with iMovie '09 won't recognise the files when I try to import them. They stay greyed, not allowing me to import them. Any ideas please.