"The blocking might be related to your use of a VPN browser plugin or program. You might try uninstalling the VPN from your computer or network and see if that makes a difference."
The Google search captcha appears when my VPN service is activated ...
At some point I thought it only occured when connecting to non - US servers but have not confirmed this
If you have some automated software who pull something from google or even just check your internet connection by pulling google.com from time to time, you will also get captcha.