Cannot join domain

Server: 2k3
Computers: XP Pro sp2

With several computers on my network they are unable to join the domain. I get the error
“The fallowing error occured attempting to join the domain : the specified server cannot perform the requested operation”

I am able to map network drives from the server. This means I can, of course, ping the server. I cannot ping the indavidual workstations from the server…

I enable the computer on the server. Then when I get the error and try to log on again I it shows up disabled.

I have also changed the workstations to different workgroups and then attemped to join the domain to no avail…

I think i got this problem once I changed the SID of the computers…