Thanks guys, I understand the problem now.
Nice try PaperT...I used your link and guess what happened. The first time I tried it the banner at the bottom of the page was for..you guessed it ... bloody Yell.com and the same problem occurred.
I think the advertisers have an obligation to ensure that their ads don't stuff things up for the people viewing the pages and as such they should be removed until such time as they are fixed
