Vista - Windows automatically removing itself from the domain

Vista ultimate 64 bit - Windows 2003 mixed mode domain. No Windows 2000 DC's but a few Windows 2000 servers. Nothing older than Win2K servers and Windows XP in the domain.

I am having a problem keeping my machine in the domain. I join the domain from the workstation, I get a successful Welcome to the domain - you must reboot prompt. I reboot and verify the computer account is now in the domain. The machine reboots and comes up to the ctrl-alt-del. I log in and there are no errors anywhere, within 30 seconds the computer automatically reboots and the next time it comes up it is no longer in the domain; the computer account however is still in the domain. I have tried this multiple times and it doesn't matter if i log in or not, within 30 seconds of the reboot the computer reboots and removes itself from the domain.

I have tried this multiple times and same symptoms. It doesn't matter if the computer account is in the domain previously or not.