Appointment problem in Outlook Calender

Hi,

I have a user using outlook 2003 and I have a Exchange 2003 server running
on net.

In his outlook if he tries to make an appointment lets say for 20'th June
(today it's 5th may) he just go to the date 20'th june and he select the time
and click new appointment useally the date shoud be 20'th june instade of
that it shows 5'th may. he needs to chane the date manually to 20'th june.

How come that it's working good on my laptop and not on his desktop. Destop
running Win XP pro.

Help....