On a window machine this could save you from lot of annoying processes but when it comes to linux When these keys are pressed together ,Your computer get restarted.
While this comes handy rebooting the machine but it is strongly recommended to disable this feature altogether.
This is how you should go about disabling Ctr+Alt+Delete.
All you need to do is modify /etc/inittab file and restart a system.
As we are doing changes to configuration file ,make a backup of /etc/inittab.
#cp /etc/inittab /etc/inittab.old
You will need to comment following line.
#ca::ctrlaltdel:/sbin/shutdown -t3 -r now
restart the system