BMM :
No idea why, but try either
Atomic Clock or checking if your PC has an NTP (Network Time Protocol) client.
NTP clients are available for
Windows 95/98/Me/NT/2000/XP/ and also in other places.
Essentially they're bits of software which talk to time sources on the Internet and correct your local clock.
Also, just found
this web site which has freeware, which I'm not sure the TimeTools site is.