(Un)Reg VBE6.DLL or restore the default VBA Editor

Moreover, I found one funny but contradict phenomenon about the "Detect and Repair" function in Excel (2000 or above):

Hey Mr. Excel, I start the "Detect & Repair" function from the "Help" menu in Excel, but you need me to turn off Excel before scanning of error? Then you should live outside of Excel as an independent doctor/menu.
Anyway, I'm appreciate if any of you know how I can (un)reg the VBE6.DLL or restore my original VBA Editor?
Colt Kwong