Help needed: spurious hyperlinks

I keep getting 'random' words underlined as though they are hyper links, but when the mouse hovers over them an advert appears, you've won an iPhone 5 or something similar. They don't seem to be site specific

I've run my Norton anti virus done the obligatory sniffing but they still appear. How can I stop them appearing?

thanks

Posted By: Claygate_Canary, Mar 25, 14:22:09