C# - Accessing The Form Collection In An IHttpModule Causes Event Handler Not To Get Called On Default Page

I've created a simple sample site to demonstrate the issue. In it, I have a Default.aspx Page that has a button on it:

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<p><asp:Button OnClick="ButtonClick" Text="Button" runat="server" />
</p>
<asp:Label ID="output" runat="server" />
</asp:Content>

The code behind just sets the label text on the button click:

protected void ButtonClick(object sender, EventArgs e)
{
output.Text = "Button Click!!";
}

I then have an IHttpModule that gets called for every request:

[code].....

And now it's broken again! So to make a long story short, just by accessing the Form collection on the request in the IHttpModule, I somehow screw up the PostBack, and the event never gets fired.