visual studio 2010 - VB.NET won't compile because of underscore -

i've been running same project on same computer months in vs2010.

there have been no code changes class contains following code:

private event valuechanged(byval sender object, byval e eventargs) _     implements sti.shared.ui.ieditfield.valuechanged 

recently, when compile, error class must implement event valuechanged.

when remove underscore , bring implements piece same line, compiles.

if undo checkout , revert code before, compiles.

it's strange behavior , i'm wondering if out there has experienced this.

i can reproduce error, slight technicallity:

public interface itest      'note here have specified system.eventargs     event valuechanged(byval sender object, byval e system.eventargs)    end interface  public class testfail     implements itest      'and here have specified eventargs, fine...     private event valuechanged(byval sender object, byval e eventargs) implements itest.valuechanged  end class  'unless declare class called eventargs in same namespace... public class eventargs  end class   public class testwin     implements itest      'it should work if prefix eventargs system though, so:     private event valuechanged(byval sender object, byval e system.eventargs) implements itest.valuechanged  end class 

and errors it: