If overclocking, undo and reset to stock speeds.
Start by reseating the memory, hard drive connections and video card, if you have one. Also might try going to the bios/uefi screen and watch the cpu temp for awhile and make sure it stabilizes at a normal temp...should be around 80 F or so at idle.
Lastly, if need be. Reset the cpu heatsink making sure that the thermal paste is covering the heat spreader.
Was windows ever loading correctly or have you had this since first install?