1. **State the problem:** Simplify the expression $$- \frac{1}{16} : (x+2)(x+2)(x-3)(x-3)$$ which means dividing $$- \frac{1}{16}$$ by the product $$(x+2)^2 (x-3)^2$$. 2. **Rewrite the division as multiplication by reciprocal:** $$- \frac{1}{16} : (x+2)^2 (x-3)^2 = - \frac{1}{16} \times \frac{1}{(x+2)^2 (x-3)^2}$$ 3. **Combine the fractions:** $$= - \frac{1}{16 (x+2)^2 (x-3)^2}$$ 4. **Final simplified expression:** $$\boxed{- \frac{1}{16 (x+2)^2 (x-3)^2}}$$ This is the simplest form since the numerator is $-1$ and the denominator is the product of $16$ and the squares of $(x+2)$ and $(x-3)$.