Screw that!

Enquiring as to train times, I discover that due to engineering works it would take over four hours to get from Cambridge to Birmingham this Sunday.

I won't be at the Birmingham game, then.

Techy Geek Question

When I turn on my PC, the PC clock always shows the right time. However, as the day goes on, it loses time, until by 5pm it's often 15 minutes slow.

When I reboot, however, the clock goes back to the right time.

Why is this? And what can I do about it?