The workaround is to compile the project to get the assemblies in the bin folder. Note, if you clean the project which removes the assemblies from the bin folder, the editor problem will come back.
We are actively working on a resolution for this issue for next release. Thanks.
Web Platform and Tools Team
3/6/2012 update: If you meet VS 11 Beta razor editor crash issue, please check http://blogs.msdn.com/b/webdevtools/archive/2012/03/06/visual-studio-11-beta-razor-editor-issue-workaround.aspx.