Well, this is a question for Compaq guys. Did you contact them ? Sounds like the keyboard or internal ribbon has some contact problems.
As for the Ctrl Alt Del combo, is your PC connected to a domain or standalone ? In either cases, there is a policy in order to restrict the Ctrl Alt Del at logon that is named:
Disable CTRL+ALT+DEL requirement for logon
Trying to unweave, unwind, unravel
And piece together the past and the future,
T. S. Eliot
Hardware: Compaq Evo 410c
OS: Windows XP Professional
Recently, my Compaq Evo 410c notebook stopped recognizing Ctrl-Alt-Del. Each of these keys work individually, but the combination is not recognized (you know what a pain it can be trying to login to Windows). I've managed to get around this by disabling the requirement for pressing Ctrl-Alt-Del to get the username/password dialog.
Now the "Fn" key has stopped working. None of the controls, like switching the video output (Fn+F4) or brightness control etc., work.
The only changes to my system have been Windows XP security patches. I have no known viruses and my definitions are up to date. I've also tried changing the default keyboard driver from MS to Compaq - but things are the same.
Could anyone suggest what I could possibly do? Maybe some hardward diagnostics that's independent of Windows? Or some diagnostic on drivers?