I'm getting the message 'Network Connection Failed' frequently when I connect to wifi using 12.04. I was using the same connection without any problems, in Ubuntu 10.04 and Windows Vista. What might be the reason why my connection is terminating so frequently while using only the Ubuntu 12.04 version? How to resolve this issue?

I have tried connecting to internet using usb Ethernet through my mobile phone. Then it worked out properly. Connection is not getting terminated as with wlan interface. So I think the problem might be with wlan modem. But then, how come wlan works well in Windows and older versions of Ubuntu. And the problem is for 12.04 alone.