Log on to domain taking longer time

It is taking a long time to logon to server.I have a log on script that greets the user based on their names.But it aint working as well.

People are not getting their mapped drives.

i had made some changes in OU of the AD.i reversed those changes.
But still the problem is the same.

when i log on to remote machine,the greeting message for user does not come up with the persons name,
but when i logon to server i get message with the username.

Can anyone tell me what is the issue in my companies network.