I get this ad at the top.
Image12.jpg
and this at the bottom
Image13.jpg, but no pop ups, and have no problems using the back button, I'm using IE.
My guess is you might has some spyware you picked up. I've had over 50 spyware programs at one time, they basically track where you go and what you buy, they are not a virus, but can slow down your computer. Some sites are really bad, especially those the graphic sites. Yorkietalk itself doesn't have any spyware associated with it, I tested. Do you have a spyware program?