A domain controller running Samba 3.3.3 will cause Windows XP clients without Service Pack 3 to crash at sartup. The process lsass.exe will fail causing a 60-second countdown and forced restart. A login is not required; This will happen at the logon prompt when the client tries to contact the domain controller.
This may be the same issue as bug #6263 referring to Samba 3.2.
*** This bug has been marked as a duplicate of bug 6263 ***