I am just starting to use the iDVD Player and am having problems. I have a disc of nature videos from National Geographic. When I mount the disc, it immediately opens iDVD and starts to play. But, as I am playing one of the chapters and try to move forward the player stops and the spinning wheel starts. So, I quit, and try again, but now that the disc is already mounted, the iDVD player does not recognize it, and there are no controls to just play the mounted disc. I keep closing the application and reopening and it opens full screen but the spinning wheel appears and nothing happens. Any suggestions? Thanks