Google's long standing disagreements with China have been a fairly public affair. Google's refusal to censor search results in that particular country have led to frequent contention between the two. The latest report to come out of this ongoing saga has Google warning users when their search queries are for materials deemed inappropriate or controversial and as a consequence are blocked in China.
Searching for particular topics in China results in an automatic disconnection from Google services over which the company has absolutely no control. Google has even checked their servers numerous times in search of the cause of the problems to no avail.
While there has been no official statement out of the Chinese government concerning a cause of the outages. With Google attempting and failing to solve the problem, it can be assumed that the cause of the problem is external and outside of Google's control.
The video embedded below depicts the resulting message if a Chinese user attempts to search for one of the search terms that has been identified as resulting in an outage. The message identifies the contentious portion of the search term and gives the user a chance to alter their search or search anyway.