logging in ->no password prompt->redisplay of login screen

Hello,

I have searched the forum but could not find any similiar
problem so I was forced to create a new thread.

I am currently logged on my Gateway 506GR running Windows XP Home Ed.
My login id has Admin privileges. There are a total of 4 valid
logins, 3 have Admin privileges, one does not.

While logged in, I decided to switch over to another Admin type
login and after entering the password, the screen flashed,
and put me rightback to the login screen. I had thought I entered
the wrong password, I re-attempted and the same thing happened.

I then attempted to login as Owner, entered the password and
the same thing occured. I then thought that maybe the password
file got corrupted, so, I switched back to the 'active' login,
went into the control panel->user accounts and I deleted the
password to the other three login accounts, then attempted to
switch user to the other logins and the same thing happened.

I even created a new userid, set the password, tried to switch
user to that userid and the same thing happened!!

Now, I am very concerned that if I were to logout of this current
login, I may NEVER be able to login anymore. Please help!!!