Assume that Microsoft Internet Explorer Enhanced Security Configuration (ESC) feature is enabled on Windows Server. In this situation, you cannot sign in to Microsoft Visual Studio 2013 Release Candidate (RC). Additionally, when you access http://app.vssps.visualstudio.com in Internet Explorer, you receive the following message:
Content within this application coming from the website listed below is being blocked by Internet Explorer Enhanced Security Configuration.
This issue occurs because that Enhanced Security Configuration feature blocks the online service URI that is needed by Visual Studio.
To work around this issue, click Add to add the required URLs into the Windows Server exclusion list, restart Visual Studio, and then try to sign in again.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.