key combination Ctrl+Alt Delete not functioning

[Alice Law]

One of my user cannot login to window. When he press
Ctrl+Alt Delete, the login dialog box no responding. Is
it means that the key combination not functioning?

I used mouse to point to the "help" button and finally I
managed to login to Window. I tried to use Ctrl+Alt
delete to lock the computer or do task manager, the 3
keys also not functioning. Later, I have tried individual
key Ctrl , Delete , Alt button, they are actually
working properly.

I do not have any idea how to troubleshoot this problem
and do not know where to check the keyboard setting?

Is this a hardware problem or software problem? How to
solve this?

 

[dev]

Alice Law said:

One of my user cannot login to window. When he press
Ctrl+Alt Delete, the login dialog box no responding. Is
it means that the key combination not functioning?

I used mouse to point to the "help" button and finally I
managed to login to Window. I tried to use Ctrl+Alt
delete to lock the computer or do task manager, the 3
keys also not functioning. Later, I have tried individual
key Ctrl , Delete , Alt button, they are actually
working properly.

I do not have any idea how to troubleshoot this problem
and do not know where to check the keyboard setting?

Is this a hardware problem or software problem? How to
solve this?

Try here first...
http://www.kellys-korner-xp.com/xp_abc.htm

Click the "C" choice, then scroll down to the <ctrl-alt-del> section.

If that doesn't do the job, the system may have been compromised by a
virus or worm.
Other suggestions will follow.