When visiting a Harry Potter site today, it downloaded something that I didn't ask it to do - it did it automatically. However ever since, I keep getting a box which says Explorer Prompt, with three "bar codes" box, Also Widnows and Fax viewer keeps coming up with xpiadv587{1}. It doesn't happen on any other website. My Norton anti virus said it had blocked something. Any advice?

The error message isn't familiar to me and there doesn't seem to be anything on Google about it. Try system scans with your antivirus and antispyware programs to see what comes up. You could also consider using System Restore to go back to a time before you visited the site.

If you manage to get the problem sorted out by one of the methods above (or suggestions by others if they come along) and are using Internet Explorer, look into securing your browser a bit. IE can be a bit prone to this kind of thing with its default settings. I believe IE7 will have different default settings to make it safer from the start.

Alternatively, consider using a different browser.

Seemed to have fixed itself for the moment. But thank you