Note that one or two Spanish banks' ATMs have the numeric-key positions reversed: the three keys you expect to see on the top will be on the bottom and vice-versa. So if you're used to typing in your PIN without looking at the numbers on the keys, you can easily lock your card.

Another thing: look at the back of your ATM card to see whether it only gives an 800 number for customer service or if it gives a full phone number with a proper area code. If it's only an 800 number (which won't work abroad), call them before you leave on your trip and find out a number that will work overseas. That way, if you *do* lock your card, you can contact the bank.

Buen viaje...