Timeout Password Problem

["Thomas H. George" <lists tomgeorge info>]

Password rejected.

When the Gnome desktop times out due to inactivity it displays a window
with my name and user name and a box to enter my password.  When I enter
my password it is rejected.

I can recover by clicking on change user.  The gdm window with entry
boxes for user name and password then appears.  I enter my user name and
password and the Gnome desktop is reopened exactly as I was last using
it.

How can I convince the timeout window to accept my password?  I am the
only user on the system.

Tom