When switching to the design view, a page containing numerous controls inside an editing region such as View or Panel may cause a crash in Visual Studio 2010. We have released a hot fix for this issue on Connect at https://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails.aspx?DownloadID=30462&wa=wsignin1.0 and on Code Gallery at http://code.msdn.microsoft.com/KB2201993.

Hope this helps.
-Anh Phan
Visual Web Developer Team.