DragAndDrop class bugged?

Hi,

I'm trying to use the drag and drop functionality of the UnityEditor classes. I had a piece of code that worked fine yesterday, but today it does not work anymore. I haven't changed ANYTHING:

 if (Event.current.type == EventType.MouseDown && Event.current.button == 0) {
     this.__draggedSection = sections[i];
     DragAndDrop.PrepareStartDrag();
     DragAndDrop.StartDrag("Dragging section");
     Event.current.Use();
 }
 if (this.__draggedSection != null && Event.current.type == EventType.DragUpdated) {
     DragAndDrop.visualMode = DragAndDropVisualMode.Copy;
     Event.current.Use();
         
 }
 if (this.__draggedSection != null && Event.current.type == EventType.DragPerform) {
     DragAndDrop.AcceptDrag();
     /*if (GUILayoutUtility.GetLastRect().Contains(Event.current.mousePosition) && this.__draggedSection != sections[i]) {
         sections[i].ConnectFrom(this.__draggedSection);
         this.__draggedSection.ConnectTo(sections[i], sections[i].tiles[0]);
     }*/
     this.__draggedSection = null;
     Event.current.Use();
 }

So today I opened Unity, opened the EditorWindow this was in and the drag and drop functionalities all were gone. Also some other weird stuff was going on. The MouseDown event was bugged; When I pressed the mouse, the MouseDown event was not triggered untill I released my mousebutton (a MouseUp event). Also whenever I was dragging, the DragUpdated event was never fired. When I removed the lines

 DragAndDrop.PrepareStartDrag();
 DragAndDrop.StartDrag("Dragging section");

The MouseDown event was behaving as normal again, but the drag functionality did not work anymore. I'm aware that I can just use regular mouse events, but I'd like to see this DragAndDrop class work properly (also because I can just easily change the cursor while dragging). Anybody encoutered this before? I work on Windows 7 Profesional, Unity 3.5.

Thanks!