Authentication Problem while connecting to WiFi

[#1]

Dear All Xperia Users...

I'm using Xperia Arc S for almost 2 month and 2 days ago, I update my Xperia to 4.0.3 and I got problem with WiFi. Although other thread already discuss this, but my problem is I can connect to the WiFi AP using WPA2 , but after maybe a moment/ couples minutes the WiFi on Xperia Authenticating something, and the result is "Authentication Problem" and my connection to the AP broke.

Note : before I update the Xperia, everything works fine until I update the phone... Is there any solution to this problem?

Thanks

[#2]

I am also facing the same problem with my Arc S after 4.0.3 update.

The phone has to be rebooted to connect again.