I get the following error message when i try to join  Windows 2003 R2 SP2 to domain:
The following error occurred attempting to join the domain "mydomain": The account is not authorized to login from this station.

Solution: On the Window 2003 Server go to Control Panel - Administrative Tools
Open Local Security Policy.  Expand Local Policies to select Security Options.  Change the following setting to DISABLED:
Microsoft network server: Digitally signed Communications (if server agrees)

Also see MS KB281648