You only need the command window open while you set the sync period, after that the Time Service re-syncs with the NTP server every [period] set by the period parameter (See w32tm /? for more info on what can be set with the period parameter, I usually go with 65532 [Once every 45 minutes until 3 good syncs, then every 8 hours), it seems to keep things very accurately set.) and you don't have to mess with the command prompt again, unless you wish to change the settings. Sorry I didn't say that explicitly in my original message.