Quote - When you delete something, Poser stores an undo point which can take a while (depending on what it is you are deleting)
Try Shift+Delete which doesn't store the undo point

I have tried to Shift+Delete  (which poser said it will delete without saving it to undo state. so i assumed that I did it correctly), yet it still lead to another "not responding". I think the undo state was not the cause of the crash.

Any other idea? Thank you!