ConfigurationErrorsException after Changing Root Namespace

Question

I am receiving the following ConfigurationErrorsException:

System.Configuration.ConfigurationErrorsException was unhandled
  Message="Configuration system failed to initialize"
  Source="System.Configuration"
  BareMessage="Configuration system failed to initialize"
  InnerException: System.Configuration.ConfigurationErrorsException
    Message="Unrecognized configuration section userSettings/Roswell.Windows.Properties.Settings.

The exception occurs in Settings.Designer.cs when attempting to return a value from the application settings file, as shown below:

    [global::System.Configuration.UserScopedSettingAttribute()]
    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
    public global::System.Collections.Specialized.StringCollection SavedConnections {
        get {
            // Exception thrown here.
            return ((global::System.Collections.Specialized.StringCollection)(this["SavedConnections"]));
        }
        set {
            this["SavedConnections"] = value;
        }
    }

Now, the interesting thing here is that we've recently shortened the root namespace of our C# application from Roswell.Windows to Roswell. After using Find in Files on all files in the solution folder and all subfolders, I can find no trace of "Roswell.Windows" in any document anywhere.

I have carefully rooted out all user configuration files on my machine that previously existed under the Application Data folder, and that produced no change in behavior: the exception still occurs.

Researching this particular issue has been difficult, at best, since the combination of involved keywords produces a great deal of noise that is hardly relevant to my issue. But this is fairly pressing, since the application fails fast (immediately at startup).

I'd really like some answers to the following:

1. Why is the .NET configuration system still looking for the old root namespace for my assembly?
2. How do I correct this?

Thank you in advance.

---

A minor correction: The one file where I can find a reference to Roswell.Windows is in the generated Manifest; but I haven't been able to locate any resource- or code-based reason for it.