I have a sandbox app that is built from the simple WPF Application template. This sandbox references an assembly that I am also building which contains the definition of a UserControl (WPF). I am instantiating this user control in the sandbox, to test the control's behaviour. The point of all this is to speed up development. This worked fine, but recently the .Vshost.exe paired with the sandbox process won't shut down. This prevents me from recompiling the Controls library, though ironically I can recompile the sandbox application. I can't kill the vshost process with Task Manager... only restarting VS2010 will clear it out. But every time I run the application from VS, the process just hangs there, blocking my workflow. I'm at a loss. Any ideas what could be causing this? Or does someone have any proposed workaround (mega-kill switch, perhaps?)