Today I spent several hours of my life trying to figure out what had broken the design view and CSS features of web pages in my installation of Visual Studio 2008. After a process of elimination, starting with uninstalling the Silverlight 2.0 SDK bits off my machine, I found that the culprit for rendering the excellent design features of Studio useless was the XML Spy 2008 components for Visual Studio. On the plus side, uninstalling the offending XML Spy pieces from Visual Studio fixed the issue without me having to completely reinstall Visual Studio, but nevertheless this was a frustrating few hours that I hope no one else has to endure.