Shows blank white box and too much padding on footer ad

On some of the ad boxes there is just a blank white box, and I’ve even seen the ads double up (duplicate ads). Also on the footer ad which is 468×60 I’m getting TONS of padding below the footer now, it just stretches the page and it’s ongoing, way too much scrolling with nothing there. There’s nothing in the code that I can see that would be causing this, and if I take out the footer ad, the scrolling is gone, there’s no extra padding added to the page.

I’m not really sure the plugin works, because there are white boxes half the time. What would cause these issues, and can they be fixed somehow?

Thanks!