Have you tried adding the machine to the domain as root? I had a problem similar to that, but when I added the machine as root, it worked fine. Also, I had a problem with when I would logon, it would work fine, but after a reboot of the client machine, it wouldn't work. I think I had to make the user's profile a local one in XP. It's under the properties of My Computer, Advanced tab, and the Settings button under User Profiles section. You might not run into this problem, but if you do, there you go.