I found the solution....
Every time you press ok on "core has stopped" and do these things. you need to be fast and step by step go to every option (annoying but you will save your phone from this mess). First Download
king root application
first root your device with "king root" app. Then go to system app remover in the king root app. look for an app name "CORE". just uninstall it and your handset is working again.
people get confused with core and acore. pls do not be confused with acore process.
a tiny app named "CORE" causing this problem. so just uninstall the app. though it is a system app, you need root permission. so root your device first.
Sorry for my bad english... :'(
