I have a Dell PowerEdge R515 running Windows Server 2003 R2 (x86) with SP2 that keeps removing itself from the domain. All the firmware and drivers are up to date. There are no missing MS patches. I can reboot the server and it'll connect to the domain but after a few hours it'll disconnect again yet I can RDP to it and login as a local admin but not a domain admin.
I have tried removing it from the domain, removing the TCP/IP stack, disabling the NICs, deleted the machine in Active Directory, I even used the W2K3 R2 SP2 DVD to run the installer to Repair the OS. Once I rejoin it to the domain it'll connect but again fail after only a few hours.
Has anyone else encountered anything like this? What can I try doing?