windows time

i have a active directory domain , with 3 DC. two of the domain controller always have a wrong time and this disturbs a lot of time depentent processes. they are always 1hr above time even when corrected, they return back after someminutes.
i even tried stopping the windows time service on the two machines but i has problems with machines loggin on to the network (they complain that ” the macines are out of time synchronisation with the server”
what is the solutioon to the above scenarios