hisense hs u8 model android phone problem

[Android Question]

I got a phone call but could not answer it, when I tried to call back this message came up: Android process acore has stopped unexpectedly. Force close.i also go the menu and use Settings/Applications/Manage Applications/ then choose the All tab. Scroll down to Contacts open it and clear the data cache. but my contact storage are not working.its completely death.plz any body help me.