What's all this computer traffic?

Q I use Windows Vista with Norton 360 and have recently downloaded the Network Meter. I find it useful as it indicates when I am connected to broadband, the security of the connection, and an indication of the upload and download speeds.

I have noticed a considerable volume of upstream (outward) traffic when I am not using the internet. I have downloaded the BBC iPlayer and, having read the introduction, understand the way it works with peer-to-peer transfer, but even with this disabled the outgoing traffic continues.

Can you tell me what this is likely to be?
Peter Record

A This traffic could be caused by all sorts of things, but you are right to be concerned by it. The most innocuous explanation is that a program on your computer is legitimately sending out data.

You don’t mention exactly how much data is going out, but remember that nowadays Windows itself and several other programs assume they are constantly connected to the internet and will be sending and receiving data at all times, even when it looks like there is nothing going on.

For instance, the Windows Sidebar may be checking weather details, news reports or stock prices, or your email program may be checking for new messages.

You’ve already discounted the iPlayer, so that should reduce the traffic (the iPlayer works by both sending and receiving programmes that you’ve downloaded, so at the same time as downloading one programme, someone else could be downloading a different programme from you).

But check the computer to make sure other networking programs aren’t running. You can check the icons in the Notification Area ­ go through one by one and right-click them and choose Exit or Close. See if that makes a difference to the amount of data going out.

The worst case scenario is that a virus or other piece of software is using your computer to send out data. It could be other viruses or spam email, for instance, and if that’s the case you should definitely stop it. Make sure your anti-virus and firewall programs are up-to-date and working.

Make sure you have the latest Windows updates (go to www.windowsupdate.com in Internet Explorer and follow the instructions to find out). Then run a full virus and spyware scan on the entire computer.