Make sure you have the most recent version of
Java (LW runs on Java.) This might be part of your problem. Also go to LW's info window (select LW & CMD+I) & increase the max RAM allocation 2-3 (or more) times depending upon how much ram you have. As for the installer, update your Java 1st & try again. From memory, the installer opens up onto the desktop, use 'that' one. Also, in OS9 it's wise to rebuild your desktop after installing/uninst'ing apps (easy way is to hold down CMD+Option keys as you restart your computer). Also use your utilities to defragment & check for errors that always seem to occur along the way.