Then run it as admin. It is supposed to blip a bit and do nothing. But then you start GOG Diablo and your Gateway should be Global, not Europe. Connecting to Europe = wrong. Connecting to Global = correct. Got it?
Anyway, this is GOG's issue to fix. It's a wrongly set up entry in Windows registry, so if you uninstall Diablo, install it again from GOG, and it still says Europe in your Gateway, then you're supposed to turn to GOG support and tell them that a fresh installation of Diablo doesn't set up your gateway properly and they should look into it.
Well the game is not allowing me to change gateway to global, so I'll probably lodge a ticket with gog then. :(
thank you for the help either way.
if anyone else has a quick fix, please tell