One user getting 401 error

One user getting 401 error

I'm working on a MVC4 project and each build gets deployed to Dev and than
QA environment. With each build, members of QA has not had issues
accessing QA site. After the last deployment one QA user is getting IE
username\password credentials. If this QA person cancels or puts her
Windows username/password in this user gets a 401 error in IE. In Chrome,
it just gives her a 401 error without asking for credentials.
She is able to go to dev environment without any issues with the same
build. So the problem is just in QA environment.
No one else having this issue(About 5 or 6 people have tried.).
The site is using Windows Authentication and everything on the IIS server
seems to be setup correct. This QA user having the problem didn't have any
issues before this last deployment either.
The server hosting is Windows Server 2008 R2 and using .NET 4.0 with MVC4.
I had the user delete all browser cache, made sure there is no proxy
server setup and made sure "Enable Integrated Windows Authentication" is
checked in IE. If any of these were not correct it wouldn't work in the
dev environment either.
Can anyone give me any ideas on the best way to troubleshoot this?
Thanks for everyone's time.