one of the coffee shops that i frequent has wifi, and recently i haven't been able to get online. it says i am connected to the network will full strength, but am not connected to the internet. i even bought my ipod touch tonight to check, and it worked just fine. everyone around me is surfing as usual... why am i experiencing this? it's been this way for a few weeks now. did they somehow block me from connecting? i've tried the network diagnostic things and no luck.