just to clarify: the domain name disappear just "from location" ? if you press "locations" button you can or can not still find the domain name?
if you have only one DC and sync this DC time with a external time source you didnt caused no harm, because since all stations will sync with DC so, even if you get the wrong time, everybody will be in sync. The only problem i can see if the external time source change the time back and forward a lot of time (a buggy time source) but i dont think that is the case.