I am newbie, not knowledgeable at all. Just purchased my first tablet Nexus 7, Wifi only two days ago. I had trouble with google play store not downloading any apps, error 495, call google tech support. After deleting data from the download manager, play store and the services framework, then their second attempt was a factory reset, and that didn't work. They recommended I return it for a software glinch. I exchanged it, same thing, What am I doing wrong? Everything works except youtube videos, (conections to server lost). I tried downloading an app on the second tablet, it errored, then did a system upgraded to 4.2.1 from 4.1.2.. Then tried downloading a different app, same thing.