I have installed Solarwinds NCM 7.5.1 in my environment. I had some database issue so my first-time installation didn't go through. After re-installing, when i try to launch the console from Start menu-> Orion Web Console, it throws the error "Service Unavailable HTTP Error 503.The service is unavailable". However if i try to access the URL from IE, it works fine.
I would check your IIS bindings for your Orion site. See if that fixes it.
If not, upgrade to NCM 7.6 and see if the issue persists.