Silverlight error message: Invalid or malformed application: Check manifest

I'm a perfectionist. I like nice namespaces. I recently created a new Silverlight project and it worked well -- until I "fixed" the namespaces. I got this message:

Invalid or malformed application: Check manifest

Checking the manifest in the XAP file revealed that my EntryPointType had not been updated to reflect the new namespaces. The Silverlight project setttings were holding on to the old name. The simple fix is on the Silverlight tab, Startup object. That combo box still has the old name.