I searched and it looks like your options are:

- Remove your Samsung account and set it up again, then restart phone.

- Factory reset. You will lose all your data, apps, settings, etc. Turn Power off. Press and hold VOLUME UP+MENU+POWER (release when it powers on). Use Up and Down volume to select from menu.

Found at:
Unfortunately samsung syncadapters has stopped on samsung galaxy s3? - It does it all the time while in the middle of doing something :: Ask Me Fast