In Leopard I'm suddenly getting very blocky, very glitchy drop shadows. Whenever I so much as mouse over the dock, I get solid blocks of shadow over the various items, and half-blocks under different windows open. Also, sometimes the open windows freeze and I have to use expose to unlock them, in which case they'll have moved almost all the way off-screen and I'll have to haul them back again. Is anyone else having these problems? How do I fix them? (I've already run the gambit of Disk Repairs on the Leopard Disk, MacJanitor, Onyx, you name it.)