I have had several different computers over the years, mainly Windows and pre-OS X Macintosh. After a while, all of these machines began behaving strangely. They would slow down, crash,and perform sluggishly. A friend said I should switch to a new Mac running OS X or even Linux because they are based on Unix, which means they are much better. My friend says all Unix machines run a special program at 3am to 'fix' things. This sounds a bit odd. Is it true? Name and address supplied For most people, the ups and downs of PCs have been a part of dealing with this new technology. Those of us who have been at it a little longer have acquired a built-in twitch on our left hand: we instinctively hit Control-S (or Command-S on Mac) to save what we are doing. This 'digital reaction' comes from more than 20 years of experience with computers that inexplicably crash or stop working. We have lived through the era of the 'blue-screen-of-death' (a Microsoft favourite) or the 'eternal spinning beach ball' (a Mac favourite) or watching the mouse suddenly freeze. The reason for this was mainly what we call 'memory leaks'. When computers run software, they must set aside memory to handle data. This is called allocating memory. It is important, however, that when the computer no longer needs that data it gets the memory back. Until recently, the responsibility for this rested squarely on the programmers' shoulders. When we run a word-processor or go on the internet with a browser, the software tends to run in loops. It waits to see if we do something with the keyboard or the mouse, performs that action and then waits for the next thing we do. It is an endless cycle of waiting, acting, and waiting again until you exit. If there is only a tiny amount of memory not being 'given back', this cycle will eventually eat up all memory and the machine will crash. Both Microsoft's XP and Apple's OS X have gone a long way to fixing this kind of problem, but neither can do so automatically. The Unix operating system has been around since the late 1960s and has had more time to fix this problem than Microsoft or Apple. The easiest way to fix memory leaks is to reboot. There are also commercial, shareware and freeware utilities that check up on your machine and can be set to run at any hour. It is a good idea to run some kind of diagnostic and 'cleaner'. One word of warning, though. Check up on any freeware or shareware software before running it. This kind of software works at a low level, and you do not want to run something that has bugs or does not work with your version of operating system. For those running Microsoft's Windows operating system, there is an added problem: the Windows Registry. The OS loads all manner of things into the Registry and every time you boot your PC, this is loaded into memory. It can be responsible for slowing things down and you can tweak it yourself, but you really need to know what you are doing. There is software available to 'clean the Registry', but the same warnings apply. Damage to this part of your computer could be very serious.
