I'm using a PC with Windows XP. I'm sure the computer is at least 16 years old.
I'm thinking I should change the battery on the motherboard.
It there anything that needs to be done before removing it and replacing it?
It seems like it's Cr2032 battery.

Thanks for the info

The 'Coin' battery has a nominal life of 10 years but I've known some to last well beyond that.
There is no specific issue with simply unclipping the old one and inserting a new one - though do make sure that the replacement is CR2032 rather than CR 2016 or CR 2020 -  and of course don't even contemplate replacement with the PC power still applied !!
The sign that the battery power is depleated is that the date/time functions are erratic but even that isn't entirely definitive.

Thanks for that info. I will change it in the next few days