Windows 2000 networking issue

Hi im having a bit of trouble with one of my cliensts networks, we have recently added a new win2k machine to the network added all the users of the other machines onto this one etc every machine see’s each other the other machines can log into the new machine and all works well IF any of the older 2k machines get rebooted then the new 2k machine cannot log in any more and i have up to now had to drop by and reconfigure everything im making one small error im sure but i just dont know what im doing wrong

the network is as follow 1 x XP home machine
2 x win 2000 machines
and the new 2 k machine

if i reboot the new box no problems occure the other boxes can still log on to that box
but if i reboot the other boxes then the new 2k box can t log into them

i know this is a abit long winded but thats my dilema

thanks for you help

sav