oh fuck a duck. (Sorry, I'm not swearing at you, I'm just swearing at that fucking bug.) You are the unlucky latest recipient of an extremely rarely occurring bug we've been trying to track down for-fucking-ever: we have no idea what triggers it, what the underlying mechanism for it could be, or how we could possibly fix it or even help you work around it. If you give us your browser/OS combination (with version numbers, please) and all your enabled extensions, we'll look into it again and see if more data helps; I may be in touch with you for some more debug information.