John is working on a Windows 7 computer that has trouble shutting down. It just keeps restarting. Leo says that's not unusual, especially for an older system like Windows 7. Chances are, the OS has never been reinstalled, and there's a lot of "kruft" that prevents an orderly shutdown (called "bitrot").
It could also be due to a flakey update that didn't install completely, corrupting a driver. At this stage, the only real solution is to back up his data, wipe the drive, and reinstall Windows. John can download a copy of Windows 7 at at microsoft.com here. He can follow these instructions to create his own install disc.