Each host behaves in its own way. Some hosts, such as aspnet_wp.exe (the ASP.NET host) and dllhost.exe (the COM+) host, exhibit a caching behavior. Sometimes when debugging using these hosts you may need to force them to recycle. When I'm coding on my own machine, the last thing I want to do is debug. Rather than reboot, I use the Task Manager to clean up or recycle host applications. If you're debugging and modifying your code and the revised code doesn't seem to exhibit the revised behavior, kill the host and try again.