Firewall warning about Microsoft Solitaire

I hardly ever play games on my PC. When I do, they're simple rather than sophisticated and all I want to do is to relax for a few minutes.

I've just tried to log into Microsoft Solitaire Collection and got this warning:

solitaire firewall alert.PNGI'm sure the site is safe so why this warning/alert? Why a warning on a site that "Norton has given a favourable rating' to? And why doesn't Norton & Microsoft speak more often to avoid nonsense like this/