The thing is, it isn't ads coming up on Firefox when I'm using it - it's Internet Explorer, which I'm not using, opening up in front of the screen with these unwanted ads.

I'd have thought there'd be some way of stopping IE opening up except when I want it to.

This has only started happening pretty recently - either my PC has picked up some kind of infection, or some new bit of technology out there has come into use allowing this to happen.