samba - Nov 2004 - XP SP2/Samba3.0.8 PDC/Directory Server 5.2 backend

Would anyone care to offer any theories (at this point I'll take 
whatever I can get) as to why the following happens:

1. w2k boxes can join the domain perfectly, users can logon, life is 
wonderful.
2. winXP boxes can join the domain perfectly, users authenticate fine, 
the screen goes blue as if it is about to load up the desktop, the 
system reboots.
3. Some errors upon relogging in with a local id about a problem with 
winlogon.exe

Nothing good as far as I can tell in the samba logs, as far as samba is 
concerned it seems to think all is well.  This one is driving me nuts...

Christian