List box is populated with data belongs to another user

I have a list box in my ASP.NET web page. The list box is populated on page load event with names of the employees of a department. The department is decided depends on the login. But when a user from department "A" logs in, he is shocked to see employees of other department in his list box i.e. other than A. He logs out and re logs the problem is solved he gets back his employees. This problem frequently occurs. What could be the problem ? Please mail togsnsarma@dotnet.itags.org.rediffmail.com orgsnsarma@dotnet.itags.org.yahoo.com

Post the code that's filling your list box.