Visual studio shows endless messages "Code generation for property 'valueMember' failed."

Try to Close and reopen the Visual Studio. maybe it seem silly, but it works!!

You can debug the designer using another visual studio and attach to process. If you got exception it should be easy to find it that way. In general when openning the designer the constructor and of course initializeComponent is running.

As this is happening at design time, it is likely that you have a custom control which requires a parameter or other value which does not have a default.

When in design view in Visual Studio; a control instance is created to render it on the visual editor, but if the control requires a property to be set before it can be rendered, it will result in an error.

Can you check that all custom controls have default values, and anything referenced in the constructor that cannot have a default is wrapped by DesignMode property - see http://msdn.microsoft.com/en-us/library/system.componentmodel.component.designmode.aspx.