Yesterday I updated to 8.1. Afterward there was an "optional update" in Windows Update for my Ralink RT 3290 802.11bgn Wi-Fi Adapter. Ut says it is a Microsoft certified driver. Installed it. Lost all ability to connect to the internet through my router
(actually you could connect to the router, but there was not internet connectivity). Rolled back the driver to the previous 6/26/2013 veriosn., Connectivity restored.
Doesn't Microsoft test these drivers before releasing them?