Can't synchronize time, Windows 7
It seems that Windows Time Service could not be started.
Check if Windows Time Service is disabled. If yes enable it and set it to Automatic (open Run prompt and type "services.msc".Navigate to Windows Time, right click, select Properties and change Startup to Automatic).
Try manually starting Windows Time Service (open Run prompt and type "services.msc"). Navigate to Windows Time right click and click Start. If it does not start properly, check the event log for the error.
If there is an error in the event log, update the question with the error.
UPDATE: Try http://www.worldtimeserver.com/atomic-clock/ first.
Very late answer here ...
After many failed attempts to sync with various time servers I came to realize time sync problems were caused for lack of an initial sync reference point. After manually synchronizing from cmd|posh I was then able to use the gui app to sync ...
Powershell ...
cd $env:systemroot\System32
.\net stop w32time
.\w32tm /unregister
.\w32tm /register
.\sc config w32time type= own
.\net start w32time
.\w32tm /resync /computer:$env:COMPUTERNAME
You should get a response such as ...
Sending resync command to {$computername} ...
Afterwards the gui interface should succeed ...