My Nexus 7 is running Android ver: 4.2.x. When I downloaded a few Apps from Google Play all went well. The Apps are: Dropbox & Flipboard, they work fine no problem. Then the next day when I booted up, I got two identical error messages in the upper left notification area: "Package File Is Invalid" for each of these two. Next I uninstalled them, rebooted, did a soft reset & loaded the apps again. Same problem. Tried several of the "solutions found both here and via Google. Not one solved the problem. Upon searching Google, this appears to be a frequent problem for many users. There's a huge number of suggestions as to fixing this, yet I've yet to find one that works for me. Since the apps work am I safe ignoring the error messages? Yet I'd rather fix it though.