IE, P3P, IFrame and blocked cookies (works until page host page has personal information requested)

Question

My company has a little widget that plugs into shopping carts. We are running into a problem where setting cookies in IE7 is not working. This is happening because we are

Answer 1

This probably won't help anyone else, but I was banging my head against the wall for weeks over this one. It turns out that IE 7 won't allow 3rd-party cookies to be set, even with a valid P3P compact policy if the HTML meta tag for Content-Type has a different character set declaration on the page with the iframe from the page within the iframe.