I found out why Movie Studio wasn't fully closing on my system. It turns out the Matrox VFW codecs that were installed as part of the lightworks video editing software (http://www.lightworksbeta.com) caused conflicts with Movie Studio. Once I removed the codecs, Movie studio closes fine, and the speed at which I can add video to the timeline is GREATLY increased (it used to take several seconds (sometimes 10-15) for the clip to be added once I drug it there).

So, if you are having the 'not closing all the way' problem or if adding clips to the timeline is sluggish, you might want to make sure you don't have lightworks installed (at least not the Matrox VFW codecs).

Hope this helps someone...