hi. I don't understand why my MPB seems to freeze while updating from 10.5.5 to 10.5.6. i left it running for one day and the bar showing the progress of the update doesn't even move a bit. i just pressed the power button to turn it off. anyone knows how to solve this? and for those who updated, is it worth? or would you suggest to leave it at 10.5.5? thank you.