Some people can’t add PC’s to a domain?

I iam charge of the PC Installation group at a large company. We recently started migration to WIN 2000 OS. I have an issue that sometimes, when logged in as local admin on a box, when I try to add that PC to the domain I will get an access deniederror. I can move down the bench to another PC and add it fine. Both PC’s were built of the same image. Another person in our group can then walk down to PC#1 and join it without difficulty. This happens to both of us, back and forth, with no apparent rhyme or reason. Help!