I just called Verizon Wireless tech support back. The guy had seen this problem once before and found a fix for it. I haven't seen this fix posted on any website, but it worked immediately. Please let me know if this works for you
Go to Settings--Date and Time--Select Date Format, and then choose a date format. Once I picked 'regional' the clock worked without the error "unfortunately, clock has stopped"
Before I tried clearing cache and doing a factory reset You don't have to do this if this "choose date format" works. Please comment and let me know if this helped you. I'm curious if this will work across the board. Maybe even for phones other than Samsung Galaxy S4. I'm stoked!
I was having the same issue. I checked the logs and found that the clockPackage.alarm has issue and throwed security Exception.
I stopped all my alarms and the error never showed up. Please report this so it is fixed in the next update.
Thanks