Crash of anything contacts-related
It sounds like a corrupted contacts file. Restore your iPad from backup, then go into iTunes and tell it not to sync contacts to your iPad. This should remove all the contact data. Now try to open Contacts. If it opens and it is empty, it is good. If it still doesn't open, then this method won't work. Assuming it opened, go back into iTunes, tell it to sync contacts again. This will add all the contacts from your computer back onto your iPad. (This assumes that you store your contacts on your computer in the Address Book app. If not, you probably will lose all your contacts...)