[疑難求助] iphone 3g after upgrade to os4 cannot connet to wifi? Everyone can help? pls.....

sonpoi79

iphone 3g after upgrade to os4.1 cannot connet to wifi?  Everyone can help? pls.....Can detect wifi, but, unable to join any network.
I had try many of wifi hotspot, same problem. Can find, but unable to join.
Anyone...help me.....

sonpoi79

Can find network, but can't join....
The msg shown
(Unable to join the network)