weird problem with crtl-alt-del system resources menu

i have a strange problem. whenever i hit ctrl-alt-del to
check my system resources (cpu usage, ram usage) or to
end a program that has stopped responding, the normal
menu does not come up. instead, i get part of the menu
(where the list of programs currently running are
displayed), and the options to end task, switch task, and
new task, but that is it. there is no heading for the
menu, no options to check my system resources, or even to
cancel. it looks like some sort of driver conflict has
occured, but i'm at a loss as to what it is.