AdSense Ads Mysteriously Rotating with Amazon Ads

Why is this Happening?

[diggle]

When I place adsense code on my pages, it works fine on most pages but on some of them instead of showing Google-related ads, it shows ads for Amazon. Does anyone know why this could be happening and what could cure it?
I do have some Amazon ads on the site.

[wrgvt]

Did you set up your alternative ad as an amazon banner?

[diggle]

Yes - but I removed the Amazon banner completely and yet still get the same effect.

[Jeremy_H]

Maybe your pages are running from a cache on your computer. Clear your cache, or try it on another computer.

[diggle]

It looks like Firefox is the problem. I looked at the site with IE and it's fine.
I didn't have a cache with Firefox.

[moishe]

I have seen the same thing with FFox, a localized bug of some kind. When i go to another PC and view with FF all is ok.

[diggle]

Thanks everyone.