Clear the cache in Storage in Settings.
If that doesn't work you might have to do a factory reset. (That uninstalls all the apps you installed and deletes all our data - pictures, music, data the apps store, etc.) so back up everything first.
If that doesn't fix it, it's time for a trip to Verizon. (The fix, until they get LolliFlop working, is to revert to 4.4.4, but you can't do that because on AT&T and Verizon Samsungs, there's a major version counter (and yours is not at 5), and you can't go back to an earlier major version. 5.0.2 to 5.0.1, yes. 5.0 to 4.4.4, no.
Thank Corporate America - they want secure phones if you're going to use them on a company network. And they don't sell non-secure versions for those of us who don't work for Corporate America. (Samsung is going to be losing a LOT of customers over their decision to "co-operate" with AT&T and Verizon on this one.)