It really has no end, isn't it? For those of you who use/have Silverlight, it was updated, too. See the MS Silverlight Release History... It all boils dow to: uninstall the previous version (probably v. 5.1.30514.0, if not earlier), because the newest installer won't do it for you, and then install the latest Silverlight (KB3056819, which has v. 5.1.40416.0). BTW, you may also find the Silverlight Balls Animation Test useful, just as I do.