Google + Tor
It seems to me that Google isn't the biggest fan of Tor...
Do a search for 'what's my IP' and you get a number of results, whatsmyip.org being the first one. Now do that same search with Tor running... I got a 403 page from Google:
... but your query looks similar to automated requests from a computer virus or spyware application. To protect our users, we can't process your request right now.
We'll restore your access as quickly as possible, so try again soon. In the meantime, if you suspect that your computer or network has been infected, you might want to run a virus checker or spyware remover to make sure that your systems are free of viruses and other spurious software.
We apologize for the inconvenience, and hope we'll see you again on Google.
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Disable Tor and once again I can run the query.