I'm trying to get a simple HelloWorld application working on my local machine using the FlexBuilder v3 Beta and the most recent SFC Flex Toolkit. I've followed the code exactly as documented in the samples found online,  various screencasts, and even in downloaded the samples. Now matter what I do, I get the following error in the login step:

[FaultEvent fault=[RPC Fault faultString="Security error accessing url" faultCode="Channel.Security.Error" faultDetail="Destination: DefaultHTTP"] messageId="274B3986-6992-1A79-1276-D7DF53D645C3" type="fault" bubbles=false cancelable=true eventPhase=2]

The login function I'm using is below:

    private function doLogin():void
    {
     var lr:LoginRequest = new LoginRequest();
     lr.username = "devlogin@blablabla.com";
     lr.password = "devloginpassword";
     lr.server_url = "http://www.salesforce.com/services/Soap/u/9.0";
     lr.callback = new AsyncResponder(loginResult, loginFault);
     conn.login(lr);
    }

What am I doing wrong?

Thanks for any help,

Mike