Strangly enough this happened today with my "main" pc ??
Never seen the clock out ever at all and today it was gaining an hour in an hour ?? wtf ?
Even after sync the clock it ran fast again,
soi'm now thinking all kinds.
So i ran windows updates and rebooted and its been fine ever since
May have been due to installing java a few days ago and not rebooting, apart from that its MS telling me to reboot.