"Unlock Computer" windows does not appear after you press Ctrl + Alt + Del

I'm having problems with a thinkpad laptop running Windows XP.  The laptop has a fingerprint reader on it, (not used).  I lock the computer and it displays the "This computer is locked and only the administrator... Swipe finger or press ctrl + alt + del" message.  However, when i press ctrl + alt + del, the message dissappears, but the "Unlock Computer" windows where I'd type my password does not appear.  

The mouse moves, the caps lock light on the keyboard goes on and off when I press the caps lock button, but I just have a blank screen.  ctrl + alt + del does not work any more.

If I reboot the computer, it works fine until i lock the computer again.
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Try this (and this is a shot in the dark), hook it up to an external monitor and see if you can see it then.  It's possible the display settings have been altered to show it on a phantom second monitor...
Try hitting CTRL+ALT+DEL
combo twice to bring up the login boxes.

If that doesn't work, uninstall the Thinkpad fingerprint security software if not being used.

Doesn't work? Something else is ailing the pc. Does booting in safe mode start sucessfully?

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See if this MS article helps>
Administrator unable to unlock a "locked" computer:

<quote>  To resolve this problem, use another screen saver program (such as Logon.scr) that is installed locally on the system or that is not corrupted.
Start Registry Editor (Regedt32.exe).
Locate the Scrnsave.exe value under the following registry key:
HKEY_USERS\.Default\Control Panel\Desktop
On the Edit menu, click String, type logon.scr, and then click OK.
Locate the ScreenSaverIsSecure value.
On the Edit menu, click String, type 0, and then click OK.
Quit Registry Editor.
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Please ensure you read the whole article for the best chance of a resolution.

Failing that, see if  'kellys-korner' has the answer>

"Control, Alt, Delete":
bootrebootAuthor Commented:
Let me add a little more information about the environment first.  The machine is a memeber of a domain.  I have a domain Screen Saver policy that enables the screen saver after 15 minutes.  According to the user, the problem only occurs after the screen saver is loaded.  If the machine is rebooted, the logon screen works fine until the screen saver is loaded again.
Find out what screensaver he is using. Could be a rouge bs one from the internet.

If its an approved one by you, you can go into screensaver properties and choose the wait time and be sure to check 'on resume, password protect' ..apply and ok. if that doesn't help, uncheck it, apply and ok. Could simply be incompatible between that screensaver and the thinkpad security software.
bootrebootAuthor Commented:
It's logon.scr.  I have the display tab hidden so that the users cannot change the screen saver or the settings.  I verified that logon.scr has not been replaced or swapped out.  Separately, it appears that the screen saver is working fine.  When I move the mouse, the screen saver shuts off and I see the "This computer has been locked" message.  When I press Ctrl + Alt + Del to bring up the password box, I can see the user's desktop background image, but the password box never appears.

I've just enroled my fingerprints and the user's fingerprings on the laptop to see if that fixes the problem.  However, now I have to wait 15 minutes for the saver to kick in.
bootrebootAuthor Commented:
I apologize for the delayed responce on this.  The user who was having this problem is only in the office monthly.  Rather than uninstalling the fingerprint software, I had him register his prints and this resolved thie issue.

Thank you.
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Windows XP

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