Proxus,
Try uninstalling your Norton Antivirus and see if it starts keeping time. Antivirus programs can cause a system clock to lose time.
Also if you have an nForce Chipset and are running Win98 it is one of the known bugs, but usually it is a system clock running at warp speed, not losing time.
It could be worth trying changing the battery but if you see it slow and speed up while the computer is running, I doubt it would be the mobo battery.
Take Care,
Richard