I have a older Windows XP desktop and recently it started freezing up, but mouse still moves, but cannot click on any of the icons. I am unable to turn computer off the normal way and have to wind up unplugging it and it comes back to normal immediately. I can use the computer as usual for a while and then it freezes again. If I unplug and plug back in and leave it alone, the screen goes black except the lower left corner start button and the lower right corner time.
a motherboard can become unreliable when its capacitors age. A number of years ago Chinese manufactures supplied many substandard capacitors to the motherboard industry. It would be much cheaper to replace the computer than to try to repair it.