login problem

in my office v r using windows server 2003 , and all clients r running in Win xp . the problem is the users unable to login in domain for the very first time in a day . so they used to restart their system and only doing so they r able to login . not every one r facing the problem daily . its occurs randomly ..... some times i used to login locally and then i used to login in domain ....

Do you have multiple domain controllers? Perhaps one of them is unavailable or misconfigured? Is it a particular group of machines / users that are having problems? What error message is displayed when logging in? Anything in eventvwr?

A bit more info and I'm sure your problem can be resolved.