Mine keeps downloading the update (from apple software update) and when I install it says something about not being able to expand the update and an error has occurred. I have downloaded the update 3 times. I have repaired permissions and also downloaded the combo update but it keeps doing the same error. I have a MacBook pro 2009. 2.53gz, 4 g ram. 250 g HD about 180gb HD space left. Please help!!