I have been working on Ubuntu (12.04) for ages now but all of a sudden I have been facing this problem for two weeks now.
I start my laptop, ubuntu connects to a wireless network and I browse for a couple of minutes on Chrome and all of a sudden the network stops responding - it shows "Resolving host" or "Connecting..." and nothing comes up. I cannot even ping any other machine or do an "nslookup" - everything fails. The wireless is still connected to AP but everything stops responding.
I have to put the system to sleep and open it again to browse for another couple of minutes and then this happens again.
Any help on this is appreciated! It has been a great pain for weeks now.