On one site - I go through surges of getting ads for bowling supplies and equipment, a lot of them for eBay.com. There is nothing in the pages remotely connected to bowling. if I refresh the page, the bowling ads might go away and I get the right type of ads for the page. I might get a skyscraper block with all 4 ads for bowling, or maybe three ads for bowling and one on topic for the pages. It almost seems that if it can't find good ads for the page, it sticks in Bowling ads as a default.
Something on your pages is triggering the ads... Go over them with a fine tooth comb.. double check the headers and footers... see if there is a keyword that might be misleading it etc. Anyone who has used Phpbb might know that you can get socked with polish ads in some cases, because there is a polish name in the footer. Also might want to use the new targetting tags to exclude non-content sections of the page to make sure none of that is causing problems for you.