The warning to fleets comes two weeks after leasing companies were told to face up to the year 2000 and beyond by David Henley, managing director of David Henley Systems.
A spokesman for fleet management software company Car Fleet Control said all its software is, and has always been, able to handle the change-over to the new century, but companies could face problems with hardware.
He said: 'Some IBM standard PCs will stop completely when the year rolls round, some will revert to 1901 and some to 1984 for no apparent reason. However, you would need to have a pretty prehistoric PC for that to happen. Quite a lot of fleets use systems they have developed in house. When that happens the systems tend to have been put together on a fairly ad-hoc basis and they could have problems.'