Visual Studio runtime Debugger is disabled

Question

I was creating an application with C# Windows Forms, and everything was fine, until today I woke up and tried running it, and it seems that it doesn't debug anything!
well, it does debug, but not as good as it used to.
For example, an obvious nullReference exception such as:

Product something = null;
MessageBox.Show(something.AllowDrop.ToString());

gives me something like this in VS:
http://i.imgur.com/l12OA.png
instead of getting the familiar, friendly UI for showing exceptions which looked something like this:
http://i.imgur.com/VtK7n.png
VS has become weird! And that's not why I'm worried: On the other hand when I'm working with a DataReader object, it skips all the errors automatically without throwing one single exception! and whenever an exception happens, the runtime tool just stops running the code!
What's going on?

Answer 1

In Vs menu Debug/Exception you should 'check'( in Common Language Runtime Exceptions) column 'User-Unhandled'.

Answer 2

Enable the Exception Assistant

Inside VS2010 go to:

Tools -> Options -> Debbuging -> General -> "Enable the Exception Assistant"