My PS3 is freezing up and slowing down?

[spanishdrgn02]

When I turn on my PS3 slim, it takes too long to load up the menu screen, when I download anything, it takes longer than usual to finish. I tried reformatting the the hard drive, but it didn't work, also when I play Assassin's Creed 2, it' takes a long time loading, voices during the cut-scenes stop then all start up at the same time. finally during game-play, the screen freezes, that never happen before, so what should I do, change the hard drive, fix the blu-ray, what cause I don't know

[striversmith]