Windows 7 has many likable and successful elements, but its clock doesn’t keep good time. In essence, Windows’ default time server isn’t good enough.
To get your system to keep better time, right-click the Taskbar clock and choose ‘Adjust date/time’. Click Change settings on the Internet time tab. Erase what’s in the Server field; then enter pool.ntp.org. Click ‘Update now’ and, after a few seconds, the clock should sync. Click Ok twice and your PC should be a better time keeper.