It was caused by a virus. Just follow the directions below.

1. Computer > Manage > Services and Applications > Services > Plug and Play

    - Startup type : Automatic. Service status : Started

2. download a vaccine program(not install)

3. Uninstall previous version vaccine.

4. unplug the ethernet(lan) cable

5. install a vaccine program(New version) & test

# If you cannot resolve this, then you will try to format.

Sorry for my English.