PC time

I have 3 network Windows XP machine on a separate domain. My problem is that whenever i change the time to the current date and time is does not stay updated to the current time. It is either 10-15 minutes behind. I have made the user apart of the admin group to see if that will help resolve the issue. still no luck ....so every 15 minutes i have to remote in and correct the time since these pc are use for store purpose and can't afford to have the wrong time on reciept. So if you have any suggestion or ideas please feel free to share.
thanks

 

Try going into your cmos and checking the time there then setting the time for windows. It worked for me on a work PC it may help here as well.