A major driver in Guam's tourist economy went down Thursday afternoon, as K-Mart's system for reaping that loot failed. Patient tourists and other shoppers waited for nearly an hour and a half until the registers went back on line. Store sources attributed this to a power outage, somewhere, though the store clearly has immediate power backup in the event of an island power failure. Less patient shoppers started abandoning carts of potential purchases, which the store was busy putting back on the shelf.