I am creating a simple animation--moving a clip across the screen in a lateral path (same Y position for both key frames, different X position). The temporal and spacial settings for the first key frame are both set to "Linear". The first and second key frames appropriately show the correct positions (starting and ending horizontal position and identical vertical position). Here's the kicker: when I play the animation, the clip moves in a gentle and slight vertical arc... and I cannot figure out why. Every other setting (ie, scale, anchor, etc is unchanged between the two key frames).