This message means that unhandled exception (aka error) happend, to user it can usally display with the raport but it only shows when app is from Google Play. In that case you can check developer way it by installing Android SDK, download offical phone driver (as you have Galaxy Nexus use Google driver that comes you can download and install with SDK menager,if you are OS X or Linux user you don't need to do that), turn on USB debugging in developer settings of your phone and and run DDMS:
Using DDMS | Android Developers
In bottom of the DDMS there a log viewer it should show all the logs that you phone is generating... including errors, it might be chaotic but you can filter it to show only errors, by adding filter (circled E icon). Now cause this to happen again with DDMS tun on and running and durning this it should show huge chank of errors on the log, on the top of this chank you should have something like this:
Code:
10-10 19:44:48.301: E/AndroidRuntime(1581): FATAL EXCEPTION: main
10-10 19:44:48.301: E/AndroidRuntime(1581): java.lang.ArrayIndexOutOfBoundsException: length=12; index=-1
the 2nd line is the reason of exception and cause of close, sometimes it's very descriptive sometimes it only shows name of exception class depending what happend, it might hint you what is wrong, but it might be something code related as my example and it's a bug that developer needs to fix, then best thing you can do is to copy whole thing (the entire error block that show up when this happens) and send it to developer together with you phone specs ;]
But copy it here (Select the log and press ctrl+c), i might figure soothing out, you can also google exception class name and it should show you what it that means
I know this is nerdy way to solve problem, but as a someone who code on Android i think this best way to figure what happens and if it's bug or something with my phone and it's better then sitting and crying if you didnt find whats wrong on internet. Usually in such things happens to Google Play app you should have Raport button and ability to see raport and see what exception happened there and you can also send it to developer from there, so in such cases you don't need to play with DDMS.