XP log on window

[John]

I have XP pro runing on Intel PIII 550. There are user
accounts created on this machine. The problem I have is,
when starts window, it goes to one user's account directly
with desk top console window and no log on window appears.
However, if log off from this user, logon window appears
and allow user to log on. If turn off the window or retart
window, again, no log on window appeares.

Someone knows how to fix this?

Thanks

John