robmiles.com

If you are using XACT you might find that you keep on getting messages telling you that a reference to an object is invalid, particularly when you try to change values in the properties windows.

This is because XACT does not work unless you have version 1.1 of the .NET Framework installed on your machine. The Requirements information makes this point: http://msdn2.microsoft.com/en-us/library/bb203916.aspx and also provides a link from which the framework can be downloaded.