Just installed 12.10 fresh. Using a run-of-the-mill Netgear N router, and a Netgear WN111v2 USB dongle.
THE PROBLEM: I attempt to install anything using update manager, software center, or via apt-get, and I can download a few megabytes no problem, and then POW. No internet connection. Connection to the router is fine, but the actual connectivity to the WAN is gone (download freezes, and no other software can access web either, including Chromium/FF). All other machines on the network continue working fine.
Now, if I disable networking and then reenable it, connectivity comes back. For a moment. I download a few more MB, and then it freezes again. And so on.
UPDATE: Now, if I attempt to load a website which has a lot of overhead (typekit, large images, etc.,), coming to a few MB, the WAN connection drops.
Importantly, I note that I used this dongle with only very occasional connectivity issues for more than year, with versions 11.04, 11.10, and 12.04. So something in 12.10 is (apparently) the culprit.