When you install the June 2006 CTP of Expression, you may find that it at first appears unstable. This is usually noticeable by the fact that it may crash when opening a project or sample. The most likely cause of this is that you had a previous version of the .NET Framework 3.0 runtime components installed.
To resolve this, uninstall the .NET Framework runtime components, and then uninstall Windows Imaging Components. You must then install a new version of the imaging components, and then reinstall the runtime components. I can find you more info on this if you need it should you run into this problem.
Read the complete post at http://www.dotnettipoftheday.com/blog.aspx?id=291