I'm having the same issue. It just recently started happening.
I have a .php page that contains the link for the call to the paypal service. Using the generated button
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
Along with all the user specific payment options.
This link appears to just be a navigation link, but somehow its generating a frame that paypal or the browser does not like.
When a user clicks the button it used to direct them to paypal for payment.
As of last week, the button is now directing them to a "This content cannot be displayed in a frame" page.
Interesting thing is I don't have a frame anywhere on the page. I assume the paypal button works correctly since it was generated on their site. My temporary fix is to add target="_blank" at the end of the first form tag.
This works fine however if users have pop up blockers, the problem now beccomes that they can fill in all the data on the page, when they submit the form to pay it gives them the blocker warning. When they accept to allow pop ups from site, it then refreshes the page losing all their entered information.
I tried adding the target="paypal" but that still requires the user to accept pop up.
Any help is appreciated.
Update: I think I may have figured it out. I have a call to code as onSubmit="return processData(this)"> This call must be triggering the pop up window blocker. When I remove this code the redirect works fine. Hm... now to figure out how to trigger the data process without triggering the popup blocker.
