user login problem in win2003 domain

i am using a win2003 domain.my problem is user can not login into domain.at the user login window when they enter username and password and domain they are unable to loggin.just for a trick they remove network chord and then enter the same info and now they logged in…i know thats pre cache settings by which is happening ..but i need to rectify this problem..can anybody help me to understand and resolve this.

Thanks in advance
Rak