Defender.lzh
While I'm not familiar with the Defender program that you are speaking of,
I have found the following to be true for most crashing programs. Either
they are unable to handle >512K of memory, unable to handle >512K chip ram,
or the default STACK is too small.
I've found that setting the STACK to 50000, cures a lot of programs.
NoFastMem helps programs that don't like fast memory, and a little utility
called KillChip, will make the 2000 look like a 512K chip ram machine.