Same thing happened to mine (was still covered under warrenty). I phoned sony they said they would probably have to replacer the laser, they picked it up on a Thursday and I had it back on a Tuesday.
Would of liked to try the possible fix posted above.
cheers for replying...i tried the reformat and stil nothing so i rangthem up and they are comming to collect i got to hand to playstation their customer support is top notch ^.^
and yes it is a 60gb ps3