Alacrity System Error

When starting W98SE, a popup window appears with Message “ALACRITY SYSTEM ERROR – OK TO REBOOT SYSTEM?” with choice of YES and NO buttons. By clicking NO 4 times, it will go away with no apparent effect on the rest of the time I’m working, either online, or off. If I click on YES to reboot, it will reboot into W98SE desktop again with the same popup message. Any ideas on cause and cure?