I just upgraded to Media 100i/xr version 8.2.2. My existing NTSC 720 clips from previous versions cannot be placed in my timeline (which clearly states NTSC 640 4:3). Is there a way to open an NTSC 720 timeline that will accomodate my clips, or is there another way around this problem?
In hardware preferences, set your video mode to NTSC 720 and then create a new timeline. This timeline will be 720, and you will be able to place your "old" clips in this timeline. I would recommend to work at 720 always anyway. This way you will avoid the problem that you cannot mix 720 and 640 media.