[Stuart]

It's an old scam.. Generally, they are trying to sell some "magic package" that will fix the "problem" they are telling you about.

In all likelyhood, it won't. It'll cost you money and send your personal details (things like Credit Card details) to them.

I had something similar a few weeks back. One of these guys phoned and told me a virus on a PC in my house was sending out data.

Now, I have three PCs. The two working ones use Avast Antivrus, and other forms of protection. So, I consider them to be fairly well protected. I have also enabled the firewall on my router. None of them were even plugged in at the point he called.

Having a degree (so I should know what I am talking about), and feeling a little playful, I decided to have fun with the caller. At one point he even said he was an MCSE, so I reeled out my CCNA (having already mentioned I had a degree).

He swore blind my PC had a virus that was sending data as he called. As I said earlier, none of my PCs were plugged in to the mains at the time of the call, and both are desktops with no UPS. I pointed this out, and that there isn't a virus on earth that can operate while it's host PC has no power.

Then I asked him for my IP (which is static) and which ISP I was on. Both would have been easy to find for him, had he been telling the truth. He was unable to give either, so I hung up.