Just noticed that all the computer clocks on a network were 5 minutes out. Went to the server (Windows Server 2008 Standard), to check the internet time synchronisation only to find that the usual Internet time tab on the clock/date control panel was completely missing. I didn’t bother investigating exactly why this is, but found the following solution.
w32tm /config /syncfromflags:MANUAL /manualpeerlist:time.nist.gov
w32tm /config /update
Obviously you can use your preferred time server instead of time.nist.gov, but run these two commands and wait a few minutes, and you should see your clock correct itself. The process will show ‘time-service’ events in the system event log to confirm your changes.