namespace problem

hi all,
I have a problem with namespaces.
I have some DLLs that implement some classes that their names much the names of others in the same solution or the class name of .Net Framework Classes

e.g.

namespace MyDll
{
   public class DataView
  { }
}

namespace HisDll
{
   public class DataView
  { }
}

namespace System.Data
{
   public class DataView
  { }
}

When I decompile the code

MyDll.DataView MyDataView = new MyDll.DataView();

I take as a result

DataView MyDataView = new DataView();

I remember I was able to see the full namespace in an older version. Actualy, I had this error in vb code but it was ok in c#, now this error applies to both.
Is there any configuration I miss?