First: What OS are you using?
If Win98:
As far as I'm aware, there is no easy way to do this other than to change the system.ini back to the line by removing the ";" from
;shell=c:\litestep\litestep.exe
and placing the ";" back in front of
shell=c:\windows\explorer.exe

then save system.ini and LogOff. This is the only way I know to do this without having to reboot.

Someone else will have to fill you in for WinXP or NT cause I don;t use either of those OS's myself.