The National Stock Exchange index, the Nifty crashed a huge 800 points this morning, bringing trade in the cash market to a halt for about 15 minutes.The bourse blamed the incident on erroneous orders worth 650 crore rupees entered by a trading member, Emkay Global Financial Services, on behalf of an institutional client. The NSE added that it was investigating the matter.The Bombay Stock Exchange said the market at its exchange was working fine, and there were no technical or other issues at the bourse. However, the Sensex had also fallen by about 200 points in reaction to the plunge in the Nifty, as there are many common stocks on the two indices.