Thanks for responding, I kept on Google-ing and managed to figure out what was wrong and was posting this post as solved when you replied.
Basically I was not initializing the Timage properly. I thought I was and it compiled okay, but.....
For anyone else searching these forums the Wikipedia article on "external sigsegv errors" puts everything in the correct context and thus helps a lot.
Also, just to finish:
"Form1.icon_map" is a TimageList
Set_image is called by TForm1.FormCreate at form creation.
That was the mistake I was making, I was trying to initialize it during the initialization section. (Okay, so I am stupid. but I learned Pascal a very long time ago and Objects really make me feel like a dinosaur.)
Anyway, thank you for your prompt attention.