I rang Microsoft for help on something else - I'd bought a dud Windows 2000 Pro CD from Direct Deals and DD won't give me a replacement.

In the course of the conversation, I asked about the Hybris and MTX viruses, which are infecting a PC I have. They pointed me to the Sophos website (www.sophos.com), which has a free 30-day download, with instructions for getting rid of worms.