Strange networking problem. Google does not work
After trying a ton of things, I got frustrated and just reinstalled Ubuntu. Since then, the problem seems to have gone away.
Some (trivial, basic) ideas
- reset your router (or at least inspect its settings)
- clear browsers' cookies & cache
- reboot (inter alia this will clear
tmp, can't harm) - try in different browsers
- try with a proxy (should almost definitely work)