Blank WiFi login screen at various public hotspots
Whenever I'm at a public hotspot that requires a login (like, say, a Panera Bread), my iPhone detects the network, then pops up a Login screen. The problem is, that screen remains blank -- I never get as far as being able to actually log in.
I've tried resetting my network settings, resetting my phone, etc. -- no soap.
A possible clue: The *one* time it seemed to work was when there was no available cellular connection. Then the Wi-Fi login screen actually appeared. But when the cellular connection was recovered, I again found myself unable to connect to that Wi-Fi network.
Help!
TIA...
iPhone 4S, iOS 6.0.2