Screensaver lockout for machine bound to AD

I need help.Seriously. I have almost 300 mac clients and i have configured to join AD domain, which is running 2003 Server. I am getting lockout issues. I am able to successfully join domain, but the moment i try to login to a mobile account that i have defined to automatically create, it automatically locks the account. I have to manually unlock it at the server's end. Also when i am running screen saver, with password security, and i am prompted with a password, i get locked out. This happens when i leave the screensaver on for about 30 mins. If i do an immediate test on screensaver, i am able to log in without any problems. Also i have set to lockout at 3 failed attempts but i get lockout on 1 failed attempt. Please help me