Can you damage a PC by unplugging it?

Q When I have finished using my computer, I shut it down and then unplug it from the socket. Recently a friend has told me this is bad practice and could damage the modem.

Nathan Brand

A We have never heard of a modem being damaged by this. It might be a case of incomplete information from your friend. An occasional, but catastrophic, source of damage to computers is lightning strikes. It’s one of the reasons for buying a surge-protected plug adapter.

Of course, unplugging the computer will also protect the computer, as long as you don’t want to use it. Your friend’s warning probably refers to the fact that the computer is still connected to the telephone, and as these cables are often in the air rather than buried in the ground they also present a risk.

The solution to this problem is either to buy a surge-protected mains adapter that also includes telephone protection, or to unplug the modem as well.

The former solution is far more convenient although it is possible to buy surge protectors just for telephone lines and at £8 they are much cheaper than replacing a computer.

It used to be said that leaving a computer on all the time reduced the stress on the internal parts but there is little practical evidence to support this view and leaving the computer on all the time will increase your electricity bill.

Finally, make sure that you select Shut down in Windows Vista. The power icon in the Start menu only puts the computer in a power-saving sleep mode by default. Click on the right-pointing arrow next to this icon and then on Shut down.

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