C# - How To Correctly Debug Web Application On Local IIS 7.5 With VS 2010 Beta2

I'm sort of new to developing Asp.net webapplication projects while running them on a local IIS. Till now I used the 'Use Visual Studio Development Server' option.

I'm using Visual Studio 2010 Beta 2.

Edit: less complex sample code

Following code sample:

List<string> _list = new List<string>();
_list.Add("asd");
_list.Add("asd2");
_list.Add("asd3");

Now I want to debug / step through some line of codes with _list. While using 'Use Visual Studio Development Server' I can see the contents of _list in the quick watch. If I select 'Use Local IIS Web server' and debug through the same piece of code, the quickwatch tries to display me the same values by showing me a spinning wheel for about 10 seconds with a resulting 'Function evalutation disabeld because a previous function evalution timed out. You must continue execution to reenable function evalution' message.

Afterwards I get a windows error dialog with 'Unhandeld win32 exception occured in w3wp.exe [844] The Just-In Time debugger was launched without necessary security permission..'

I do run Visual Studio 2010 Beta 2 as Administrator. I start debugging by pressing F5. It seems that I can't really debug this way. Do I somehow have to attach the VS debuggerto the IIS process? If yes, how to do so?

What am I doing wrong, and how to solve it?

And by the way, is that erroneous behaviour new in VS 2010? I've never expierencied that in VS 2008.