If you are running Windows Vista or later you can try my Active Directory UDF (for download please see my signature below). The _AD_Open function returns detailed error information in case of an error. This and more errors are handled: 525 - user not found 52e - invalid credentials 530 - not permitted to logon at this time 532 - password expired 533 - account disabled 701 - account expired 773 - user must reset password The validation code could look like: #include <AD.au3