In windows Vista, when trying to debug you might get this error
"Unable to start debugging on the web server. Debugging failed because
integrated Windows authentication is not enabled. Please see Help for
assistance"
FIX:
Go to Start "Control Panel"
Programs
Under Programs and Features click on "Turn windows features on or off"
a Windows Features dialog will appear
Locate Internet Information Services and expand it
Locate World Wide Web Services and expand it
Locate Security and expand it
Locate Windows Authentication and make sure its checked
Than just reboot your machine
Once it reboots, go to Start "Control Panel"
"System and Maintenance"
"Administrative Tools"
Locate IIS and double click on it
A IIS dialog will appear. locate your project and click on it. on the right you should see in blue IIS and under it Authentication, click on it
right click on Windows Authentication and Enable it.