I’m busy repairing/reinstalling a few different PCs right now, so excuse the condensed format of this post, but if you run a WordPress based site, and have just noticed two strange boxes (transparent frames in this case) appearing on your page, you may want to check if you have the ShareThis plugin installed. If so, temporarily at least, untick the facebook like option. Not sure if this is a fb API change, or if share this have altered the javascript called from within the plugin, but once the fb like button is not requested, the annoying frames seem to disappear.
Thanks to Ira for bringing the issue to my attention 🙂
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It seems others have noticed it too – see the ShareThis forum here.