Michael, I am only blaming the programs based on the facts. When I originally purchased FCS 2, and started using Motion 3, I had nothing but crashes and freezes, on two different computers. I worked with Apples Motion team who surmised that is was indeed a software problem, which they corrected in the 3.0.1 and 3.0.2 releases. While nowhere near perfect, Motion definitely preformed better after the updates.
Since upgrading to Leopard, the crashes have started again, and much worse this time. Using Motion, and Motion content in FCP, is most often the cause of the app and OS crashes. I am fairly sure that Leopard has something to do with the horrible instability of Motion...
As for 3rd party plugins...I have DVMATTE PRO for FCP, CGM blur slide, and Gfilm converter.
The only thing else I have installed are drivers for my WACOM tablet, EPSON printer, and an HP printer. They are all the most current Leopard compatible drivers.