I've found that if you have a timepicker control that's blank, you focus it, you begin to type something in such as 5 then scroll the mousewheel before the value was committed you get a 4004 error. The error is fairly long but for the most part it says System.InvalidOperationException: Nullable object must have a value. It would be nice to have a property that allowed us to disable mouse scrolling for controls such as this to prevent people from accidentally scrolling anyway.