Basically around the 2000s we had a WinXP computer and each time I wanted to use it, either my mom or my dad had to turn it on. However they had to strike the key to enter the BIOS. Everytime when booting the PC. Then they would exit the BIOS and so Windows XP would boot normally.
Do you guys know if your parents also did that and why?
Could be a dead CMOS battery, but if the computer had a case switch more likely it was a security feature that lets you know the case was opened. On Acer computers you would have to press F1 to continue the boot, or Del key to enter the BIOS and have the chance to change the setting. Incidentally the setting is usually under the Security tab> Open Chassis. You can reset the notification or turn it off.
I run into this situation on office computers all the time, because no one knows how to turn it off or reset it.