Warning: this video is slow with lots of waiting time on the errors. View the video and original post by Michel Wester at State of Search.
After searching for specific phrases on Google search users in china will get a “page not available” error for about a minute and a half. This prevents the user from completing the search and also completely blocks them from Google.
It appears that this error is the fault of Google but after the Google team did careful analysis they found that its not them causing the error. It appears to be censorship. Google has adapted by inserting a warning that services might be interrupted for specific phrases.