The problem might be because of any Installed third party application or the media card can you try removing the media card to see if that helps !
If that fails I would suggest you to Reload the OS to rule out any Software issue , But after reload leave all third party application for a few days to see if they are the culprit ,Use a selective restore i;e only Contacts and calender entries don't install any apps from your backup.If problem don't appear install only BlackBerry Native apps. So first do a backup using Desktop Software then Reload your device Software , for help refer to this Knowledge base :
