I don't know what changed, apps updated before. I get the update notices, but then it shows "error retrieving information from server (RPC:AEC:0) " ???
I got this error when I first got my N7 and did a system update. I tried clearing the cache, then clearing the data for Google Play, which didn't work. I ultimately did a factory reset (which wasn't a hassle since my device was brand new)--that did the trick.
I thought about doing that, I have a lot of apps. I'll wait now as I emailed Google Tech. Come to think about it, it may have started after the system update.