Yeah no problem. From what I gather it's gdm/kdm/xdm that forces a respawn. ctrl+alt+backspace I think kills X but the gdm/kdm/xdm tries to restart X, hence why you would need to kill one of those in order for the ctrl+alt+backspace to kill x permanently... As for his problem, he might want to just stick with ctrl+alt+backspace, because that would restart his X (or kill it) and stop the program that is giving him trouble. It's different from ctrl+alt+del but unless he wants a restart it gets the job done.
So in the end, the OP should worry about ctrl+alt+backspace unless he wants a restart. Though I have noticed that sometimes XFCE (probably a glitch in xorg) will not do anything when you press those buttons, though currently it works for me. I would just say on linux try ctrl+alt+backspace first before using the del key instead.