1. The default server, time.windows.com, is just not as reliable as some other NTP servers publicly available. However, the best practice now is to sync to a NTP pool and/or your local university's or ISP's NTP servers. Get the list of servers for your location at the NTP Pool Directory. Example: 0.us.pool.ntp.org 1.us.pool.ntp.org 2.us.pool.ntp.org 3.us.pool.ntp.org
2. Run the following commands from an Administrator command prompt:
net stop w32time
w32tm /unregister
w32tm /unregister (yes, again)
w32tm /register
net start w32time
w32tm /config "/manualpeerlist:0.us.pool.ntp.org,0x9 1.us.pool.ntp.org,0x9 2.us.pool.ntp.org,0x9 3.us.pool.ntp.org,0x9 time.windows.com,0x9" /syncfromflags:MANUAL
w32tm /config /update
3. Now you can check to see which server you are currenly connected to:
w32tm /query /source
w32tm /query /peers
4. To sync your PC's clock to the time server's manually at this point (it will update according to the default schedule):
w32tm /resync
That should do it!