logon failure: account currently disabled

I have windows 2000 domain server.There are 15/16 clients of win. 98 & win XP.A win XP client which is in a workgroup can access all users but any client and server is unable to access that. when i want to access it on server it displays “logon failure: account currently disabled” but i checked logon account is not disabled. I can’t understand whats a problem?