Quickly logs off

I have an XP user who logs into a NT4-domain/Netware5.0
network. Sometimes when she tries to login the login
screen will disappear, after she enters her password, and
then it looks like it will log her in but instead it
routes her right back to the CTRL-ALT-DEL logon screen.
She has to cold boot her PC a couple of times before this
is temporarily resolved. Does anyone have a resolution for
this?

Thanks,