  For a finite subgroup $\Gamma\subset \mathrm{SL}(2,\mathbb{C})$ and $n\geq
1$, we construct the (reduced scheme underlying the) Hilbert scheme of $n$
points on the Kleinian singularity $\mathbb{C}^2/\Gamma$ as a Nakajima quiver
variety for the framed McKay quiver of $\Gamma$, taken at a specific
non-generic stability parameter. We deduce that this Hilbert scheme is
irreducible (a result previously due to Zheng), normal, and admits a unique
symplectic resolution. More generally, we introduce a class of algebras
obtained from the preprojective algebra of the framed McKay quiver by a process
called cornering, and we show that fine moduli spaces of cyclic modules over
these new algebras are isomorphic to quiver varieties for the framed McKay
quiver and certain non-generic choices of stability parameter.
