Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
WIFI Problems Hit iOS 6 Users
So earlier today Apple released iOS 6 to the public and at first sight it appears to have been a launch / release with out any problems unlike iOS 5 which was hit with a 3200 error message.
Within the last 30 minutes we have had multiple emails from readers telling us they are suffering from a problem with WiFi in iOS 6.
It appears when some users are connected to WiFi they are presented with the a login screen which is Apple.com.
From what we have heard it appears when users connect to open networks WiFi is working fine