I want to transfer my vacation video to an external hard drive (1TB) which has been correctly formatted to my IMAC. My problem is when I click on the little button at the top of the event block which than shows all available discs the hard drive I want has a yellow triangle with an exclamation point in the centre. I have tried everything possible to drag these events to the external hard drive but no luck. I have tried dragging photos and other folders to this external hard drive with no problem. Anybody got any ideas what the triangle is telling me and how I can get this vacation movie backed up to the external hard drive so I can start working on it? As the video is a total of 24 days and HD it is taking a lot of room on my hard drive