The first step is to open visual studio 2010. Select "Tools" menu and select "Options" item from it
From the Options dialog box expand Debugging node from the left tree view and then select Just-In-Time node listed under the Debugging node.
In the right pane check all the three options if they are unchecked.
In the config file please ensure that the "compilation" tag should have "debug" attribute set to "true". As shown below.
In visual studio, Right click the .aspx page and then set IE as default browser.