Saturday morning shoppers checking their Keno tickets in retail stores on early on Saturday morning may have been misled as to whether or not they had won a prize when technical problems affected the accuracy of the checking system.
New Zealand Lotteries says customers who had their tickets checked between 6.30 am and 9.20 am would have been told their ticket had not been a winning one, whether or not that was true.
Once the problem was identified, the Keno checking system was turned off for repairs, and was in operation again by 10 am.
Chief Executive Todd McLeay says Keno players who had their tickets checked during the three-hour period should get them re-checked.
He says that if people have thrown their ticket away they should go to their Lotto store and fill out an incident report form.
New Zealand Lotteries says only one high-value prize was won in Friday night's draw and that was an on-line purchase.
An investigation will be held into the system failure.