It could be just one of those annoying things with computers that they very occasionally freeze. The first thing you notice is that your mouse pointer will not move and then, to your disappointment, you find that striking any key on the keyboard has no effect either.
Under these circumstances, all you can do is to shut down the computer by holding down the "on button" on the computer for 5 or more seconds.
When your computer restarts you may come to a black screen with white writing and be asked the question whether you want to start in "Safe Mode" or "Start the Computer Normally". Choose "Start the Computer Normally". If computer continues to freeze after it has started up, then there is a problem. Otherwise, you may find the computer works perfectly for many months before any repeat of the problem.
Your computer hard disk has a limited life span and this may range from 3-6 years depending on the frequency and amount of usage. Be warned, however, that hard disks occasionally fail before reaching 3 years of age and so you should always backup your important data.
As the hard disk reaches the end of its life it may begin to experience issues such as failing to read and write data accurately, overheating, and mechanical failure.
Your computer may freeze if your hard disk fails to read data correctly. Such a fault may be intermittent i.e. sometimes the data is read correctly and sometimes it is not. If your computer needs some data that is critical to the operating system, and it cannot read it, then your computer will likely come to a grinding halt.
If you hard disk is getting old, the best thing you can do is to create an image of the hard drive and copy this image to a new hard drive (before it is too late). You need special software such as Acronis True Image to do this.
All it takes for your computer to freeze is a momentary loss of electricity either to the whole computer or to an individual component inside. If you are having shut downs and freezes, the first thing you should check is whether the power lead to your computer is plugged in properly to the computer or the power board. It is really easy to dislodge a power lead with your foot.
You should also suspect that the power board itself could be faulty.
Very commonly, with old computers, the issue is inside the computer. If there is a bad connection between your memory modules and your motherboard, or between your video card and your motherboard, then a momentary loss of electricity flow could occur. In either case, reseating the memory modules or video card cures the problem in a large percentage of cases.
A typical scenario in aging computers is that video card (if you have one) becomes faulty. Although, video cards have cooling fans or cooling vanes, they can become hot if the fan or vanes become clogged with dust. This is one good reason to clean your computer yearly. Excessive heat is an enemy of your computer and component failure can result.
The power supply unit is another component that can fail but usually, if it does, the problem is that computer won't start at all. Nevertheless, the power supply unit may be the cause of the problem.
It is also possible that your motherboard may have a faulty component. This is a hard one to be sure about. If you keep getting freezes and you have eliminated everything else, then it may be your motherboard that is the problem. If you have a desktop computer, the experience computer repairer can install a new motherboard in about 30 mins if it comes to this. However if you have a laptop, the job may take 1½-3 hours. Furthermore, laptop motherboards are usually more expensive than desktop motherboards.