I had the same problem where all of my user's accounts got locked out every morning. Then during the day, they would be locked out for no apparant reasons. To resolve my particular problem, I closed the null session on all of my DC. The key is:
HKLM\System\currentcontrolset\control\LSA
RestrictAnonymous is set to 2

Cheers,

Diana

------------------------------------------------------------------------
---
Your network firewall and IDS products do not prevent Web application
attacks - the most common form of online exploitation- resulting in Web
defacement, data theft, sabotage and fraud.
KaVaDo is the only company that provides a complete suite of Web
application security products.
Download a FREE whitepaper on "Security Policy Automation for Web
Applications":http://www.securityfocus.com/Kavado-focus-ms
------------------------------------------------------------------------
---

[ reply ]