I would suggest that you unplug any hardware connected to the PC and then reboot. This includes keyboard and mouse.
Once rebooted reconnect each item in turn, if you get a reboot post plugging in an item then the fault could be with the hardware you have just connected.
If this does not work run system file checker, start, run and type sfc. it will run automatically.
If this does not work then reboot to safe mode and run defrag.
Still not booting, try a selective boot up.click here