After I relocated an IIS express application, it stopped working. Even though I re-registered it with Visual Studio, it appeared "stuck" in its old location. The problem is that Visual Studio doesn't tell you that it hasn't really done anything at all when it claims that it's successfully registered your app after you've moved it. After reading this FAQ I was able to delete the broken site registration and then re-add it in Visual Studio. To fix my problem, I ran "%userprofile%\documents\IISexpress\config" from the Windows start menu, did a ctrl-F to find the application name, and simply deleted the configuration node.
IIS Express FAQ : IIS Express : Microsoft Web Platform : The Official Microsoft IIS Site: "Q: Does IIS Express use the same configuration system as IIS 7.x?
A: Yes, IIS Express uses the same applicationhost.config and web.config files supported by IIS 7.x. The key difference is that with IIS Express, the configuration is maintained on a per-user basis. In particular, whereas IIS has a global “applicationhost.config” file, IIS Express maintains a user-specific “applicationhost.config” file in the %userprofile%\documents\IISexpress\config” folder. This lets a standard user run IIS Express and also lets multiple users work on the same machine independently, without conflicting with each other. Some settings require Administrator user rights to set and modify (see question above about running as a standard user)."