Q:

Why does ExpandoObject not work as expected? 

Currently, not even the simplest examples of using the 'ExpandoObject' work on my machine. 
Both 
dynamic obj = new ExpandoObject();
obj. Value = 10;
var action = new Action<string>((line) => Console. WriteLine(line));
obj. WriteNow = action;
obj. WriteNow(obj. Value. ToString());

(from this website) and
dynamic sampleObject = new ExpandoObject();
sampleObject.test = "Dynamic Property";
Console. WriteLine(sampleObject.test);

(from the MSDN examples) fail with a RuntimeBinderException.  I presume I've misconfigured something, but I am at a loss about what it might be. 
I am using .NET v4.0.30319 and Visual Studio 2010 SP1 Premium.  Please ask for anything else you might need to know.  =)

A:

Deleting the hidden "SolutionName.suo" file in the solution directory fixed this problem for me.  
I still have no clue why it occured, though. 
Edit: 
Andras Zoltan, who deleted his answer, guessed correctly.  I have had "Break on all Exceptions" enabled and was being stupid.  =)

