PlatformIntegrationDemo WebAuthenticator problems on emulator?

[plettb]

This is likely a machine configuration issue, since I'm trying this on two different machines. When I try the "Web Authenticator" sample, it works on one of my machines, but fails on the other. I click "Microsoft" and the failure looks like this:

Unfortunately I have no idea where to begin looking for the problem. Any help would be much appreciated!

Thanks in advance.