Watch out for system proxy settings in Ubuntu Desktop 11.10 (at least in its LXDE guise, which is what I am running in a VM). The control panel "Network" has disappeared and even if you install it using apt or Synaptic you'll find that it doesn't have any proxy options. gconf does, but seems to have no effect. Answer is to edit /usr/share/applications/chromium-browser.desktop and append
to the Exec line.