Maximum PC: Shopped at a Barnes & Noble brick-and-mortar store lately? If so, keep a close eye on your bank account. The book vendor issued a statement today warning that it's aware of tampering with PIN pad devices at 63 of its stores spanning from California to Rhode Island, and several states in between. B&N called it a "sophisticated criminal effort" in which a single PIN pad was compromised in each of the 63 locations.