Signs that the turn of the century could cause problems for computer systems emerged when credit and charge card swipe machines issued by HSBC Holdings started erroneously rejecting purchase requests. Retailers across Britain have been suddenly forced to start making purchase authorisation requests manually, creating long queues at cash tills across the country. The problem first emerged on Boxing Day, which usually marks the first day of the post-Christmas sales, when stores can be at their busiest. Officials said the glitch found in the swipe machines, which were manufactured by the British group Racal Electronics, could easily be eliminated by keying in a short code. 'The problem is minor,' an HSBC official said. 'It is basically to do with the failure to recognise the first day in 2000.' Although the turn of the century has not yet taken place, the affected computer terminals perform an internal diagnostic check that looks at the machine and all the transactions that have taken place through it. The diagnostic check tends to work days in advance, and has started malfunctioning because it is failing to recognise January 1, 2000. To avoid the problem, retailers are being advised to enter a code that will disable the checking system. Racal said the glitch would automatically rectify itself after the change of the century. An HSBC official said the number of retailers affected was small. It is understood about 10,000 to 14,000 such terminals were manufactured by Racal, and about 10,000 retailers have been affected. However, this accounted for only about 2 per cent of outlets that accept cards throughout Britain, Racal said. 'We are confident that the terminals will return to full functionality by the end of the year,' Racal spokesman Nicholas West said. HSBC said it had brought in extra staff to man its help lines, and had set up a phone service at processing centres to inform retailers how to solve the problem.