ACS External Windows Authentication: Pre-Windows 2000 name only works

Question

Hello. I have attempted to map ACS to Windows AD 2003 as an External Database. That works, but only if I authenticate using the Pre-Windows 2000 name (sometimes called the "down-level" name).
If I use the Windows 2003 login name, I get a 529 error in the event viewer, stating the username/password is incorrect. This error appears on the Windows 2003 SP1 server running ACS.
Curiously, if I authenticate using the down-level name, the successful event shows the same authentication package (MICROSOFT_AUTHENTICATION_PACKAGE_V1_0) and "Workstation" and "Login Process" name (CISCO).
I cannot determine if this is an ACS or Windows problem. Any one have a clue?

Answer 1

Win2003 logon name: [email protected]
A Pre-Windows2000 name: [email protected]
Interestingly, the down-level name will authenticate, but the "up-level" name will not.
Here are excerpts from AUTH.log:
Failed up-level name:
AUTH 01/19/2006 07:52:04 I 4817 3604 Attempting authentication for Unknown User '[email protected]'
AUTH 01/19/2006 07:52:04 I 0365 3604 External DB [NTAuthenDLL.dll]: Starting authentication for user [[email protected]]
AUTH 01/19/2006 07:52:04 I 0365 3604 External DB [NTAuthenDLL.dll]: Attempting Windows authentication for user bob.smith
AUTH 01/19/2006 07:52:04 E 0365 3604 External DB [NTAuthenDLL.dll]: Windows authentication FAILED (error 1326L)
AUTH 01/19/2006 07:52:04 I 0365 3604 External DB [NTAuthenDLL.dll]: Reattempting authentication at domain COMPANY
AUTH 01/19/2006 07:52:04 I 0365 3604 External DB [NTAuthenDLL.dll]: Attempting Windows authentication for user bob.smith
AUTH 01/19/2006 07:52:04 E 0365 3604 External DB [NTAuthenDLL.dll]: Windows authentication FAILED (error 1326L)
AUTH 01/19/2006 07:52:04 I 2124 3604 Unknown User '[email protected]' was not authenticated
Passed down-level name:
AUTH 01/19/2006 07:52:23 I 0365 3604 External DB [NTAuthenDLL.dll]: Starting authentication for user [[email protected]]
AUTH 01/19/2006 07:52:23 I 0365 3604 External DB [NTAuthenDLL.dll]: Attempting Windows authentication for user bsmith
AUTH 01/19/2006 07:52:23 I 0365 3604 External DB [NTAuthenDLL.dll]: Windows authentication SUCCESSFUL (by WINDC02)
AUTH 01/19/2006 07:52:23 I 0365 3604 External DB [NTAuthenDLL.dll]: Obtaining RAS information for user bsmith from WINDC02