That's not something you can do very easily or at all through vb.
Those two key combos are operating system interrupts (ctrl + alt + delete has the highest priority of any interrupt).
If you want to get rid of them (or at least their functionality) you should look into some software like Fortress that locks down the operating system.
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Its a frigging Laptop, not a Labtop!!!!
Im not too sure about VB but C++ allows for the development of keyhooks that you might be able to use to intercept any keys that are pressed and make them perform another action!
btw it sounds like you are tying to code a trojan?