I know that is a pretty specific title, but after wrestling with this problem for the last couple of days (with a break in there for a very nice weekend!) I figured I would try to put something specific enough for Google to index it and so that some poor soul might benefit from my frustration.
The WPF designer randomly crashing is not an uncommon thing – Google it and you will see that the solutions are hit and miss and somewhat black magic. Things like – pin the toolbox when opening a file or create a new XAML file and that randomly fixes the old ones. My is no less black magic as I have no clear explanation for it – but it worked for me.
My issue was that XAML files in certain projects would load just fine, but in certain other projects Visual Studio would crash hard. Finally I removed the Presentation.Core and Presentation.Framework from one of the two projects that were having this problem and added them back. And Voila! problem fixed for not only that project, but also the other one as well. I know – random and inexplicable – but thus is the Cider designer in 2008 SP1. Hopefully this solves your WPF designer woes as well!