The ban orders were issued by the Central Government Procurement Center as a part of its efforts on use of energy saving products.
Zinhua, the official news agency of the Chinese government, has that this step has been taken to ensure security of the computer system after Microsoft ended support for Windows XP.
No details were provided by either the government or Zinhua that how this ban is related to energy efficiency or how it improved security.
Chinese market has always been a hard nut to crack for Microsoft. Steve Ballmer once reportedly said that that Microsoft earned even less revenue in China than it earned in Netherlands due to piracy reasons though the computers sold in China were equal to those in U.S.
Microsoft had announced that Windows XP was end of life since last month which means that Windows XP users are exposed to hacking and vulnerabilities.