I have not been able to use the dialer/keypad or log/history in the Phone app on my Samsang Galaxy S3 since an Android upgrade about four months ago. Whenever I opened them I would get the message "Unfortunately, contacts has stopped". And in order to dial numbers I would have to save them as a contact first.
It is a bug in Android that causes certain configurations to have no valid date format, which in turn causes Contacts app to crash this bug. The workaround solution is so trivial, it is embarrassing for Samsung and Google that they have not fixed this bug yet;
I hope this blog post helps more people find the solution more quickly than I did. (I found the solution on Android Central.)