A virus has wiped out every single computer at all of Portsmouth's libraries.
The computer virus, which struck first just before Christmas, has infected the entire Portsmouth City Council library network.
It means no-one can log on to any library computer in case their personal details are compromised.
Technicians have been working on the fault, but as every computer is infected, it is likely to take up to two weeks to get them all back on line.
However, North End and Cosham branches could be fixed within a week.
The city's library services manager, Lindy Elliott, said: 'The virus had hit two of the computers at Southsea Library, on Elm Grove, and we thought we had managed to get rid of it. But it must have been transmitted into the entire system and now it has come back. It's proving very difficult to get rid of. Two weeks is our guideline, but of course we hope it will be a shorter time than that.'
One concern is that the virus may be able to hack into people's personal details, though there is no evidence this has happened yet.
Ms Elliott said: 'We think that is possible, but we don't think it has happened yet. We just want to make sure we are as safe and secure as possible, which is why we're just saying no-one should use them until we're certain the virus has gone.'
No-one yet knows what the virus is, though it's thought to be similar to a number of Russian programmes, which have hit websites and computers across the world.
But the council is confident it has been uploaded innocently.
Ms Elliott said: 'We definitely don't think it's been maliciously put on the system. It's most likely someone has logged onto a site and it's come in through there. It's the first time anything like this has
happened and we're working very hard on it. We hope it will take less than a fortnight, but it's just to give some warning to people.'
Muriel Deacon, of the Portsmouth Pensioners Association, said: 'A lot of our members do go to use the computers, because maybe they can't afford to buy one or run one from home. It's a shame for them because it's a good way to stay in contact with people. I hope they can sort it out in less than two weeks.'