Clock on Powerbook in error

Appreciate tips on the following. I use a 17inch Powerbook (OS X) at home and use a 17 Inch Powerbook (Windows) at work. I noticed at home (yesterday) and in the office (today) that the clock on the powerbook is slowing. This is the date and time at the bottom or top end of the screen. I corrected the times but found that they slowed down later even up to slowing down to an hour behind.

Hope to hear some suggestions on what I can do to fix it.

Have you ran the DST updates for both operating systems? Are both operating systems set to go to the internet to pull time from an atomic clock like time.apple.com or time.windows.com?

Be sure both OS X and windows are completely up to date.