Technical difficulties my a**. It's clearly the fear.
China is falling, Europe is falling,.. not a great day for trading..... unless you trade Bitcoin, of course

Europe is not failing. Greece is just one insignificant country without strong economy and possibilities they are not even close to being core of the EU.
NYSE stop is caused by technical problems with their computer system. Technical difficulties and network errors are not exclusive NYSE problems today - United Airlines and newspaper "Wall Street Journal" had it too.