Unable to start program 'http://localhost/Default.aspx'. VS2010

Question

I cannot start my website from Visual Studio 2010 anymore.

For a few days I cannot start my project in a web browser using F5. When I open my web application directly by

Answer 1

Had same problem, answer for me was to remove Avast Free AV. Everything worked for a year with avast free up until a week or so ago, uninstalling it fixed the problem.