Script combination causes loss of hot keys

When I include the shell script below with AppleScript instructions either before it or following it to do other things, there is a very good chance that when the whole script has run its course I will have lost all my hot keys in applications like QuickSilver and QuicKeys.

do shell script "sudo pmset -a dim 1" password "myPW" with administrator privileges
do shell script "sudo -k" -- timeout sudo ability

This loss does not seem to include key equivalents in application menus like command-save, etc., doesn’t have any effect on mouse position or button behavior, and works without this effect all by itself.

Can anyone hazard a guess or suggest a solution?
[OS X 10.3.8]