Embedded object runs unsigned, but fails when signed.

[Greg Stangler]

After clearing all CAS policies (caspol -q -reset), I access the component
defined below through an embedded <object> tag in a simple html page.

When the assembly is unsigned , the MessageBox displays, but when the
assembly is signed the component no longer runs. I suspect that this has
something to do with the AppDomain the IE is running in and what it does to
check policy.

Can someone explain why this benign component succeeds when it is unsigned,
and fails when it is signed. I'm confused because the component is benign,
and makes no attempt to access protected resources.

Component Sample: Create as windows library (VS2003) or windows control
(Whidbey)
=================================================
using System;
using System.Windows.Forms;

namespace testspace
{
public class MyComponent : System.Windows.Forms.UserControl
{
public MyComponent ()
{
MessageBox.Show("MyComponent is Alive");
}
}
}