Scans.
https://askleo.com/what_is_the_system_file_checker_and_how_do_i_run_it/
http://www.howtogeek.com/howto/windows-vista/guide-to-using-check-disk-in-windows-vista/
recently, my internal network card got fried during a lightning. after that computer just wont shut down. it restarts everytime i shutdown/sleep. i replaced it with a new external nic. but the problem persists .

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