I imagine as soon as my recommendations are published, my inbox will be inundated with everyone's special theory as to why we should/shouldn't shut down our machines. Being a fair and unbiased individual and in true democratic style as befits an election year, I will present my take on the subject and you can do whatever you want.

First, we have to dispel a few myths, namely that: * Your data "wears out". * Computers remember everything forever.

* Data can be easily recovered if your hard drive fails. * Viruses "burn" sector 0 of your hard drive.

* Computers "don't like" being restarted. * Smoking banana skins gets you smashed. Computers are electronic devices, like a TV or microwave and should, in essence, be treated as such. Hard drives and fans, pretty much the only moving parts in a computer, are like any other mechanical device - they wear out with use.

Take the old car-engine theory, which hypothesises that car engines would last much longer if we left them idling all the time because they love to run and hate being started from cold, which apparently wears the engine out faster than if it were left running. Dinner-table physics supports this theory to an extent, but this is the real world and external factors are at play; our cars/computers operate in wildly diverse conditions and environments, all of which have an impact on longevity. This means that for anyone to stick their neck out and state categorically that either course of action is the best opens themselves to the inevitable "yeah, but what if . . ." questions.

It seems then that it would take a brave (or stupid) soul to stand up and recommend we turn off or keep running. Well, I'll give it a shot. Let's look at some facts: computers generate a lot of heat. Generally speaking, the faster your computer, the warmer it will run. This plays havoc with the guts of your machine. The main component is a large printed circuit board, which has thousands, if not hundreds of thousands, of components soldered onto it. Any electrical-type person will tell you that solder is not very strong, breaks down over time and makes a poor electrical connection.

Physics tells us that when something gets warm, it expands and when cooled, contracts. When you fire up your machine, everything inside swells, then when you turn it off, it shrinks. Solder joints are especially susceptible, as is your hard drive and RAM and expansion card sockets.

So, there's a pretty good argument for keeping your machine running and maintaining a constant case temperature. The downside is that, as I mentioned, moving things wear out. Physics again tells us that when surfaces move against each other, friction causes wear and energy is released in the form of heat. Heat accelerates the process because surfaces expand and rub harder, generating more friction and heat, which also compounds the whole expansion/contraction issue. Hard drives hate heat. Then there's the fans, which are notoriously unreliable. Your computer may have as few as one or as many as six, most of which are critical to your machine's wellbeing. They do a lot of work and when they choke up with dust or just wear out, they slow down - or stop altogether - and fail to keep things cool.

This causes system instability and often leads to spectacular hardware failure. Yes, some computers are designed to run 24/7/365 - usually servers that are specially built for the job. Even their operating systems are coded to run for extended periods without restarting. Generally, home computers are not.

While XP and Vista are better than previous versions of Windows, for various reasons they still like to be restarted every now and then. It also wastes a lot of power and costs you money when your machine is running. The computer doesn't really care if it is being turned off or not; it just does what it has been told or designed to do. Therefore, we must look to common sense for the answer; you wouldn't leave your car or your TV running all night, so why your computer? Me? I turn mine off and so far it hasn't fallen apart. And in this green age, I recommend you do the same.

The Press, New Zealand