If you're using AdBlock Plus in Chrome / Chromium, there was a bug[1] that caused this behavior whenever it blocked an iframe-based ad. It's been fixed in Chro

If you're using AdBlock Plus in Chrome / Chromium, there was a bug[1] that caused this behavior whenever it blocked an iframe-based ad. It's been fixed in Chromium but the fix has yet to work its way into Chrome stable. 1. https://code.google.com/p/chromium/issues/detail?id=178380 https://code.google.com/p/chromium/issues/detail?id=178380