I have Dell D600 notebook and use it with docking station.  
 
When i pluged in to docking station my external keyboard (standard keyboard from dell GX270) and at startup when windows XP login screen appears I can't press ctrl+alt+del combination !
It doesn't work at all on extrenal keybord...
 
I have to open my notebook and press this keys at notebook's keyboard.    
This is very weird and verrry uncomfortable ....
 
 
I being looking quite a long time for solution and still didn't find it

maybe keys on external doesnt work at all or atleast one of them

is it just the first time at logon screen or you still cant use it in windows or after reboot?

@pogsnet
external keyboard is working perfectly, except pressing combination of ctrl+alt+del ...  when I plug it in another PC they are working ...
I used few diffrent keyboards (PS2 plug) and it's not working.
 
@ilivgillgill
combination of ctrl+alt+del doesn't work at all, even when I login using standard keyboard from my notebook - nothing happens when i press those keys