You ever figure this out?Sorry about the silly question,so i reckon i deserved a correction of sorts.
I guess i am the sort who does'nt like to just go buy something until i know i have exhausted all possibilities.I would like to mention at least 3 points here.The drive is very easily removeable from underneath.You could first pop the whole drive out after booting and popping the tray open and leave it partially out.Then,you could inspect it,and try gently cleaning the lense.I also noticed,when putting it back,that it takes a very firm push to have it fully seated.When it was not,it did exactly as your problem,just passed it by on boot.Heh,does it read any data disk ok,autoplay an installation disk?
I also noticed that if the laptop was passworded(several options there),the lappy acted a bit odd and booting was lengthily dragged out with a black screen.
Lastly,your best bet for a replacement will be ebay,but it's not super cheap or anything.Hope it works out,now i can say i made some senseable input,lol.