What to do with the same message constantly popping up on screen?

These are the two continuous messages that pop up on my screen:

Unfortunately, Calendar Storage has stopped.

Unfortunately, the process android.process.acore has stopped.

They each only give one option which is to press 'OK' underneath the notification for it to disappear. However it only does disappear for a few seconds and hence forth can't use the phone at all ! AND it is brand NEW !!!!!!!!!!!!!

What on earth should I do to fix this...???

I tried rebooting the phone and removing the battery.. Basically everything that is listed to help in the manual book for frozen phones etc. Please help?