Vista Hates Windows Domain

I have a Vista box I installed a while back. I put it on the domain and everything was all fine. Well, one day, I noticed the box wasn't named what it was supposed to be and being kind of OC about that, I changed the name. After I rebooted, the box had removed itself from the domain. hmm. I put it back on. I logged on with my domain credentials and all was great. Till I rebooted again. Once again, removed. It wouldn't let me put it on again because the computer was still in the AD list, so I renamed it. Then rebooted. Then put it back on the domain. Logged in. Rebooted (to test it)... BAM! off again. I've even tried putting it on a different domain it's never been on. Still removes after reboot. Haven't found the cause yet, but I think that's really weird.
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Update:
I think the box isn't really removing itself from the domain. While logged on, it has all the resources and otherwise acts like it's on the domain. The real problem seems to be it doesn't allow domain users to log on. I don't get an option to switch users on the login screen (there is one local user), therefore, there is no box in which to submit my domain credentials. I thought I found people with the problem, but they were just confused because you have to now use the format domain\user or user@domain.