Your Are Not Authorized to access visualstudio.com

I can't login to Team Foundation Server from within Visual Studio, I get the following error:

"Your Are Not Authorized to access visualstudio.com"

I have a project stored on visualstudio.com that I'm trying to launch within Visual Studio 2013/2015.  When I try to open the project and login, I get the following error:

Your are not authorized to access https://xxxxxx.visualstudio.com/defaultcollection

The error is slightly different depending on how I initialize the login.  If I launch the project from visualstudio.com, I get this error:

If I just try to connect from within Visual Studio, I get this error:

The login worked fine on my old PC, but it doesn't work on my new PC.  I compared proxy settings, which are identical.  I then realized that my old PC was running IE 10, but my new PC is only running IE 8.  Upgrading to the latest version of IE fixed my issue.