User on AD and Sharepoint are different

I had same issue: Open ad and find the user, right click and choose properties.  check if everything is ok at the account tab, such as firstname last name... If it is correct or not do the following: dont just correct from the account tab, bcz it wont apply the changes!  To rename the account, right click it and choose rename, this will take to rename firstname and last name and display name...

Let me know if it works

it didn't work i renamed it to the same name with small letter and it still points to Kevin Smith

Can Kevin log in to the site?  If so, it's only his display name that is out of sync.

What version of SharePoint?  Do you regularly sync user info with AD (through the SSP or User Profile App)?

yeah user can log in into sharepoint.  Sharepoint 2010. I don't know if we regularly sync the user with aD.. How can we  do taht?

If Karrie Smith used to have the same username, then probably she is put in the content database of that site collection. As it doesn't seem like you have the user profile service running, remove the user from the site collection and add it again. You will have to reapply the security settings though (if you did that on user base)

You need to create a user profile service app, create a connection to your domain and run a sync. Do a quick google search for a guide.

Where this is the article you should use to set up the user profile service:
http://www.harbar.net/articles/sp2010ups.aspx

Technet is up to date now too, but I still follow this one to set it up.

I've requested that this question be deleted for the following reason:

no one answered

I'm guessing creating the UPA didn't resolve the issue, based on his last response.  In that case, the command I posted in comment ID: 39091840 will solve and should get points.