It has not yet been announced whether the Christmas shopping season turned out to be a bonanza for retailers in Switzerland. But if it proves to have been, the Zürcher Kantonalbank can claim a small share of the credit . Not in the way you might think, however. Apparently, "a couple of things went wrong" earlier this month when bank staffers were testing a new computerized salary-disbursement system for civil servants, a spokesman explained. The test was programmed to assume that everyone on the government payroll was due a nominal payment of 1 Swiss franc, or 77 cents in US money. Alas, the computer did more than assume; it officially generated the payment for each of the more than 40,000 people involved. Now what? Well, rather than try to compel the recipients to give back the money, bank administrators decided to write off the full amount - roughly $31,000 - on grounds that the collection effort surely would cost more than it would recover. The message, in other words: Think of the windfall as a bonus and feel free to put it toward Christmas gifts.