将一个ASP.NET 1.1的应用程序通过VS 2005转换为ASP.NET 2.0项目后，编译时出现这样的错误：“Error 19 The type or namespace name 'ControlDesigner' could not be found (are you missing a using directive or an assembly reference?)”，代码中使用了System.Web.UI.Design.ControlDesigner，出现这个错误是由于没有引用System.Design。于是在VS 2005中添加该引用，却出现错误：
A reference to 'System.Design' could not be added. Error parsing application configuration file at line 17. Type'{http://www.microsoft.com/practices/enterpriselibrary/08-31-2004/configuration}ReadOnlyConfigurationSectionData' is not found in Schema.”
卸载Enterprise Library后问题依然存在，后来，发现在该应用程序的web.config中留有Enterprise Library的配置<enterpriselibrary.configurationSettings>，删除该配置后，问题解决。